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Full text of "The ants of North America."

Bulletin of the Museum of Comparative ZoSlogy 

AT HARVARD COLLEGE 

VOL. 104 



THE ANTS OF NORTH AMERICA 
BY WILLIAM STEEL CREIGHTON 



WITH FIFTY-SEVEN PLATES 



CAMBRIDGE, MASS., U. S. A. 

PRINTED FOR THE MUSEUM 

April, 1950 



The Ants of North America 

BY WILLIAM STEEL CREIGHTON 
College of the City of New York 



CONTENTS 

Introduction 

The Present Status of Ant Taxonomy and Nomenclature. 

The History of Ant Taxonomy in North America 

Family Formicidae 

Key to the Subfamilies 

Subfamily Ponerinae 

Key to the Genera of the Subfamily Ponerinae 

Genus Stigmatomma Roger 

Key to the Subspecies of Stigmatomma pallipes Haldeman . . 

Genus Platythyrea Roger 

Genus Ectatomma F. Smith 

Subgenus Parectatomma Emery 

Genus Proceratium Roger 

Key to the Species of Proceratium 

Genus Sysphincta Roger 

Key to the Species of Sysphincta 

Genus Neoponera Emery 

Genus Pachycondyla F. Smith 

Genus Euponera Forel 

Key to the Species of Euponera 

Subgenus Brachyponera Emery 

Subgenus Trachymesopus Emery 

Genus Ponera Latreille 

Key to the Species of Ponera 

Genus Leptogenys Roger 

Subgenus Lobopelta Mayr 

Key to the Subspecies of L. (Lobopelta) elongata Buckley . 

Genus Odontomachus Latreille 

Key to the Subspecies of Odontomachus haematoda Linne . . . 

Subfamily Cerapachyinae 

Key to the Genera of the Subfamily Cerapachyinae 

Genus Cerapachys F. Smith 

Subgenus Parasyscia Emery 

Genus Acanthostichus Mayr 

Subgenus Ctenopyga Ashmead 

Subfamily Dorylinae 

Genus Eciton Latreille 

Key to the Subgenera of Eciton 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Subgenus Labidus Jurine 

Key to the Species of Labidus (workers) 
Key to the Species of Labidus (males) 

Subgenus Neivamyrmex Borgmeier 

Key to the Major Workers of Neivamyrmex . 

Key to the Females of Neivamyrmex 

Key to the Males of Neivamyrmex 

Subfamily Pseudomyrminae 

Genus Pseudomyrma Latreille 

Key to the Species of Pseudomyrma 

Subfamily Myrmicinae 

Key to the Genera of the Subfamily Myrmicinae . . . 
Genus Myrmica Latreille 

Key to the Species of Myrmica 

Genus Manica Jurine 

Key to the Species of Manica 

Genus Pogonomyrmex Mayr 

Key to the Species of Pogonomyrmex 

Subgenus Pogonomyrmex Mayr 

Subgenus Ephebomyrmex Wheeler 

Genus Stenamma Westwood 

Key to the Species of Stenamma 

Genus Aphaenogaster Mayr 

Subgenus Attomyrma Emery 

Key to the Species of Attomyrma 

Genus Novomessor Emery : 

Key to the Species of Novomessor 

Genus Veromessor Forel 

Key to the Species of Veromessor 

Genus Pheidole Westwood 

Key to the Species of Pheidole 

Subgenus Macropheidole Emery 

Subgenus Pheidole Westwood 

Genus Epipheidole Wheeler 

Genus Sympheidole Wheeler 

Genus Cardiocondyla Emery 

Key to the Species of Cardiocondyla 

Genus Crematogaster Lund 

Key to the Species of Crematogaster 

Subgenus Orthocrema Santschi 

Subgenus Acrocoelia Mayr 

Genus Monomorium Mayr 

Key to the Species of Monomorium 

Subgenus Monomorium Mayr 

Subgenus Parholcomyrmex Emery 

Genus Xenomyrmex Forel 



CREIGHTON: ANTS OF NORTH AMERICA 



Genus Solenopsis Westwood 

Key to the Species of Solenopsis 

Subgenus Solenopsis Westwood 

Subgenus Euophthalma Creighton 

Subgenus Diplorhoptrum Mayr 

Genus Epoecus Emery 

Genus Anergates Forel 

Genus Erebomyrma Wheeler 

Genus Myrmecina Curtis 

Key to the Subspecies of Myrmecina americana Emery 

Genus Macromischa Roger 

Key to the Species of Macromischa 

Genus Leptothorax Mayr 

Key to the Species of Leptothorax 

Subgenus Goniothorax Emery 

Subgenus Dichothorax Emery 

Subgenus Leptothorax Mayr 

Subgenus Mychothorax Ruzsky 

Genus Symmyrmica Wheeler 

Genus Harpagoxenus Forel 

Key to the Species of Harpagoxenus 

Genus Triglyphothrix Forel 

Genus Tetramorium Mayr 

Key to the Species of Tetramorium 

Genus Xiphomyrmex Forel 

Key to the Subspecies of Xiphomyrmex spinosus Pergande 

Genus Wasmannia Forel 

Genus Cryptocerus Fabricius 

Key to the Species of Cryptocerus 

Subgenus Cryptocerus Fabricius 

Subgenus Cyathomyrmex Creighton 

Genus Strumigenys F. Smith 

Key to the Species of Strumigenys 

Subgenus Strumigenys F. Smith 

Subgenus Trichoscapa Emery 

Genus Cyphomyrmex Mayr 

Key to the Species of Cyphomyrmex 

Genus Mycetosoritis Wheeler 

Genus Trachymyrmex Forel 

Key to the Species of Trachymyrmex 

Genus Acromyrmex Mayr 

Subgenus Moellerius Forel 

Key to the Subspecies of A. (Moellerius) versicolor Pergande . 

Genus Atta Fabricius 

Subfamily Dolichoderinae 

Key to the Genera of the Subfamily Dolichoderinae 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Genus Dolichoderus Lund 

Subgenus Hypoolinea Mayr 

Key to the Species of Hypoclinea 

Genus Liometopum Mayr 

Key to the Species of Liometopum 

Genus Iridomyrmex Mayr 

Key to the Species of Iridomyrmex 

Genus Forelius Emery 

Genus Dorymyrmex Forel 

Key to the Subspecies of Dorymyrmex pyramicus Roger 

Genus Tapinoma Forster 

Key to the Species of Tapinoma 

Subfamily Formicinae 

Key to the Genera of the Subfamily Formicinae 

Genus Brachymyrmex Mayr 

Genus Camponotus Mayr 

Key to the Subgenera of Camponotus 

Subgenus Camponotus Mayr 

Key to the Species of Camponotus 

Subgenus Tanaemyrmex Ashmead 

Key to the Species of Tanaemyrmex 

Subgenus Myrmentoma Forel 

Key to the Species of Myrmentoma 

Subgenus Colobopsis Mayr 

Key to the Species of Colobopsis 

Subgenus Myrmothrix Forel 

Key to the Subspecies of C. (Myrmothrix) abdominalis Fabricius 

Subgenus Myrmobrachys Forel 

Key to the Species of Myrmobrachys 

Subgenus Myrmaphaenus Emery 

Key to the Species of Myrmaphaenus 

Subgenus Manniella Wheeler 

Genus Paratrechina Motschoulsky 

Key to the Species of Paratrechina 

Subgenus Paratrechina Motschoulsky 

Subgenus Nylanderia Emery 

Genus Prenolepis Mayr 

Key to the Subspecies of Prenolepis imparis Say 

Genus Lasius Fabricius 

Key to the Species of Lasius 

Subgenus Lasius Fabricius 

Subgenus Chthonolasius Ruzsky 

Genus Acanthomyops Mayr 

Key to the Species of Acanthomyops 

Genus Myrmecocystus Wesmael 

Key to the Species of Myrmecocystus 



CREIGHTON: ANTS OF NORTH AMERICA 



Genus Formica Linne' 

Key to the Subgenera and Groups of Formica 

Subgenus Proformica Ruzsky 

Key to the Species of Proformica 

Subgenus Raptiformica Forel 

Key to the Species of Raptiformica 

Subgenus Formica Linn6 

Species Belonging to the rufa Group 

Key to the Species Belonging to the rufa Group 

Species Belonging to the microgyna Group 

Key to the Species Belonging to the microgyna Group . 

Species Belonging to the exsecta Group 

Key to the Species Belonging to the exsecta Group .... 

Species Belonging to the fusca Group 

Key to the Species Belonging to the fusca Group 

Subgenus Neoformica Wheeler 

Key to the Species of Neoformica 

Genus Polyergus Latreille 

Key to the Species of Polyergus 

LITERATURE CITED 

INDEX 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

INTRODUCTION 

During the years that the writer spent on the preparation of this 
volume its character changed completely from what was originally 
intended. When Dr. W. M. Wheeler proposed, in the fall of 1936, 
that we collaborate on a field book of North American ants, his idea 
was to prepare a keyed catalogue similar to that which Emery pub- 
lished on the ants of Italy in 1916. No revisionary work was con- 
templated and the publication was to include keys and distributional 
data which would aid in field studies of our ants. This seemed an 
excellent idea, for, many summers spent collecting ants in all parts of 
the United States had convinced me of the need for a single, concise 
volume which could be carried into the field. I gladly acceded to 
Dr. Wheeler's proposal and began work on the book. Dr. Wheeler's 
death occurred in the following spring, before he had made any active 
contribution to the volume. This left its preparation entirely in my 
hands. As I worked over the material in the Wheeler Collection, the 
need for revision became apparent. At that time current concepts 
relating to speciation were beginning to take shape and there seemed 
to be abundant opportunity to apply these concepts to ant taxonomy. 
With this in mind I undertook not only to prepare the necessary keys 
and to collate the vast amount of distributional data in the Wheeler 
Collection, but also to revise the two infraspecific categories employed 
in ant taxonomy. 

The complexities of ant nomenclature have been considered in the 
section which follows this introduction. They need not be discussed 
here, but it seems advisable to state that, as a result of the revisionary 
work presented in this volume, it has been necessary to treat a large 
number of forms as synonyms. In 1947 Dr. M. R. Smith listed 742 
species, subspecies and varieties of ants which have been taken in the 
United States. In the present work only 585 of these are recognized 
as valid taxonomic entities. Despite this reduction, the number of 
species has been increased, for it has been necessary to accord full 
specific status to many forms previously regarded as subspecies. 
Moreover, there has been surprisingly little need to synonymize 
previously recognized species. Hence, the great majority of the 157 
forms which have gone into the synonymy have been subspecies or 
varieties. The end result has been to eliminate the variety as an 
infraspecific rank. For all the varieties which have been retained as 
valid show the characteristics of geographical races and have, for this 
reason, been given subspecific rank. 

In the case of some species which originally possessed a large number 
of subspecies and varieties, revision has radically altered the character 



CREIGHTON: ANTS OF NORTH AMERICA 9 

of the assemblage. Under such circumstances it has seemed advisable 
to present a single account of the changes involved. This discussion 
is placed immediately after the name of the species but ahead of the 
bibliographic citations and other data relating to it. Although this 
represents a departure from the customary treatment, it is believed 
that the method will be of substantial aid to the reader. It permits 
a comprehensive view of the revision within the species. It also avoids 
repetition, since the same revisionary considerations can often be 
applied to several of the variants simultaneously. 

The bibliographic citations carried for each species and subspecies 
have been extensively edited. It is no longer practical to present full 
bibliographies for many of our species. In recent years many regional 
studies dealing with the distribution of our ants have been published. 
Much use has been made of such studies in preparing the ranges pre- 
sented herein. But I cannot feel that this type of publication should 
be listed in the bibliography of each species which it covers. It has 
been assumed that if the reader of this book finds it necessary to look 
up references given under the various species, it will be because he 
wishes to secure a fuller knowledge of the structure of the insects than 
can be obtained from the keys. Considerable effort has been made to 
see that all such references apply to descriptive material or to points 
which elucidate the taxonomy of the species involved. Papers which 
carry only distributional records have been placed in the general 
bibliography at the end of the volume. 

Since much stress has been placed on the importance of distribution 
in this work, I wished to present the ranges of the species and sub- 
species in a way which would be both accurate and concise. After 
considerable experimentation with various methods I doubt that there 
is any entirely satisfactory way by which this can be done. If all 
known records are cited the result is an accurate but clumsy list,which 
requires analysis by the reader before it conveys any impression of 
the range. At the other extreme are those over-simplified statements 
which announce that a species occurs in the northeastern United States 
or in Sonoran areas of the southwest. Such statements leave nothing 
to be desired as far as brevity is concerned, but they are as vague as 
the first method is cumbersome. The plan followed in this volume 
represents a compromise between these extremes. I believe that it is 
accurate enough to give the reader a satisfactory picture of the range 
without overwhelming him with a mass of details. 

Another point related to distribution involves the question as to 
whether the territory covered in this book warrants the title chosen 
for it. I make no excuse for the title employed, or for the fact that 
I have excluded those species in Mexico and Central America which 



1U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

do not enter the United States. A political boundary is rarely a bio- 
logical terminus. As far as ants are concerned North America has no 
southern limit. In extreme cases the range of a species may extend 
from the central United States to northern Argentina. Hence for 
practical purposes one may as well select the political boundary which 
most closely approximates the natural boundaries of major faunistic 
groups. From this standpoint the northern border of Mexico serves 
best. Our extensive Nearctic ant fauna is largely confined to regions 
north of Mexico and the few representatives of this fauna which occur 
in Mexico are strictly limited to the higher mountain ranges. The 
reverse situation applies to the tropical element of the Mexican ant 
fauna. A number of genera and subgenera commonly encountered 
in Mexico and Central America have no representatives in the United 
States. In other cases Neotropical genera possess only one or two 
species which enter the United States, and these species rarely range 
more than a few miles north of the Mexican border. The large Sonoran 
component of our ant fauna is equally abundant on either side of the 
border. But portions of this fauna extend throughout much of South 
America, hence it must be given an arbitrary southern limit in any case. 

Unless otherwise noted all keys in this volume apply to the worker 
caste. The important part played by this caste in ant taxonomy is 
often misunderstood by those who contend that sound specific dis- 
tinction must rest upon the characteristics of the sexual forms. There 
is no objection to this view, but there are practical considerations 
which limit its application to ant taxonomy. For very obvious reasons 
the worker caste is far more likely to come into the hands of the 
collector. In most ant colonies the sexual forms leave the nest soon 
after they have reached the adult condition. Because of this, the 
period during which all three castes can be taken together is, ordi- 
narily, a very limited one. Moreover it is often impossible to secure 
the queen when a nest is discovered. At the slightest disturbance to 
the nest the queen will hide herself in its most obscure part and exten- 
sive excavation may fail to exhume her. These circumstances have 
greatly reduced the number of males and females taken in association 
with workers. As an example, there are sixty-three species and sub- 
species of Pheidole included in this volume. The worker caste of all 
of these has been described. But the female caste has been described 
in only twenty-six cases and the male caste in no more than eighteen 
cases. This proportion represents a reasonable approximation to what 
is found in most of the larger genera. Until a higher percentage of 
females and males can be associated with the workers it is not advis- 
able to present keys for the identification of the sexual forms. 

The introduction to this volume would not be complete without 



CREIGHTON: ANTS OF NORTH AMERICA 11 

reference to the individuals and groups who contributed in various 
ways to its production. Of these the late Dr. W. M. Wheeler stands 
first. The writer not only benefited from a personal association with 
Dr. Wheeler but also from his generosity in the gift of a large number 
of identified specimens which he and others had described. Other 
myrmecologists who have generously contributed material are Dr. 
M. R. Smith, Dr. C. H. Kennedy, Dr. A. C. Cole, Dr. G. C. Wheeler, 
Dr. L. G. Wesson, Mr. W. F. Buren, Mr. W. L. Brown, Jr. and Mr. 
G. S. Walley. Without these specimens the work would have been 
seriously hampered. 

A very important contribution was made by the American Philo- 
sophical Society, which provided a grant to cover the preparation of 
the illustrations. With this grant the services of Mrs. Shirley Risser 
were secured, and it is due to her care and skill that the illustrations 
of this volume were produced. I am indebted to the Board of Higher 
Education of the City of New York for granting me leave during 
which most of the work on this book was done. I also wish to thank 
Harvard University for a research fellowship during 1938 and the 
Museum of Comparative Zoology for providing research facilities and 
for allowing me access to the Wheeler Collection. Thanks are due to 
the American Museum of Natural History for similar privileges. 
I wish to thank the Wheeler family for permission to examine Dr. 
Wheeler's unpublished manuscripts. 

The arduous task of proof-reading the original type-script was 
undertaken by Mr. W. L. Brown, Jr. His care and thoroughness have 
eliminated many minor errors which might have entered the volume. 
I wish to express my sincere appreciation to Mr. Brown for this 
valuable assistance. 

In conclusion, I venture to hope that, despite its revisionary char- 
acter, this volume may fulfill the purpose for which it was originally 
intended. By his unsparing efforts Dr. W. M. Wheeler built up a 
superb collection of North American ants and produced a large body 
of literature dealing with them. Both must be constantly consulted 
by anyone who hopes to do significant taxonomic work with our species. 
But Dr. Wheeler was aware that work in a library or a museum is 
only a part of the taxonomic picture. He never lost sight of the impor- 
tance of field work and it was his wish to arrange matters so that such 
work could be done accurately and without constant recourse to type 
specimens and original descriptions. If subsequent events show that 
field work on our North American ants can be done with more ease 
and accuracy because of this book, I will feel that it has fulfilled 
Dr. Wheeler's wish and that I have been amply repaid for the time 
and effort spent on its preparation. 



; BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

THE PRESENT STATUS OF ANT TAXONOMY 
AND NOMENCLATURE 

The myrmecologist may count himself fortunate that he has to deal 
with a group in which specific characteristics are so clearly and easily 
discernible. Most ant colonies are composed of the offspring of a 
single female. This female usually mates but once and at that time 
she receives from the male the entire supply of spermatozoa which 
will subsequently fertilize her eggs. These sperm cells are all genetically 
identical, since the male ant is haploid and produces spermatozoa 
directly, without meiosis. The relationship of the workers produced 
by such a female is, therefore, a peculiar one. As Dr. George Snell 
has pointed out, they are not only sisters but half -identical sisters. 
From the standpoint of their genetic constitution there is every reason 
to believe that in those ant colonies which possess a single queen, the 
workers should show a much greater uniformity of structure than 
would be found in a population where both parents are diploid and 
where repeated insemination from random mating occurs. The hered- 
itary constitution of the worker caste in most ant colonies is as rigidly 
controlled as that of animals experimentally bred in a genetics labo- 
ratory. It is not sound judgement to apply to the population of an 
ant colony, the same considerations that would have to be used for 
a group of individuals selected from the general population of a non- 
social species. The two groups are not genetically comparable and, 
because of this difference, the ant colony is far easier for the taxono- 
mist to handle. It may be doubted that many myrmecologists have 
concerned themselves with the reasons for this fact, but they have 
been fully aware of the fact itsslf and have profited greatly by it. 
When a student of ants observes that certain characters are constant 
throughout the entire worker population of a colony, he knows that 
this constancy has not been due to any attempt on his part to select 
or arrange the population with an eye to uniformity. The personal 
equation in specific delimitation is thus reduced to a minimum because 
the myrmecologist is blessed with material which advertises its own 
specific characters. When these same constant characters are repeated 
with an equal constancy in colony after colony, the myrmecologist 
need not be blamed if he feels that his specific criteria are as well 
founded as it is possible for such things to be. 

If the characteristics which occur in an ant colony are so favorable 
to taxonomic work why has the myrmecologist involved himself and 
his field in such an altogether horrendous maze of nomenclature? 
Why not be satisfied with the well-marked species that nature has so 
obligingly provided and let it go at that? The difficulty arises mainly 



14 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

By current standards Emery's system is unacceptable, but this has 
not been the main reason for the many objections which have been 
directed at it. The subordination of the variety to the subspecies has 
made ant taxonomy so complex that it has become unmanageable. 
There have been numerous proposals designed to alleviate this situa- 
tion. I shall speak only of the one which I made in 1938, since the 
remedy suggested has proven a very poor panacea indeed. I proposed 
to do away with the varietal rank altogether and treat all infraspecific 
variants in ants as subspecies. This proposal was based on the belief 
that most subspecies and varieties would prove to be geographical 
races when they were better known. If my surmise had been correct 
the preparation of this book would have been greatly simplified. It is 
always easier to suggest that a form be elevated to a higher rank than 
to show why it must be sunk as a synonym. The main difficulty has 
been with the varietal rank. I now know that I was wrong in supposing 
that most of our varieties can be treated as geographical races. Amaz- 
ingly few of them have the distributional characteristics which such 
races should show. This is particularly true of varieties based upon 
color. These color varieties almost never possess any distinction of 
range that would separate them from the 'typical' form. The two 
occur together over a common range and there is usually a high degree 
of intergradation between them at all points of this range. I regret 
to say that numerous color varieties have been set up, although it 
was recognized at the time of original description that the type series 
consisted of intergrading material of this sort. In such cases the 
definitive varietal characters will apply to only a part of the type 
series. This peculiar situation is certainly irritating, for it shows the 
low regard in which the variety has been held even by those who 
elect to name them. The more I have studied color varieties, the more 
I have been surprised to discover how little justification there is for 
the recognition of most of them. These varieties possess no distinctive 
distributional features. There is no constancy in the color characters 
which are supposed to define them. Their recognition involves prac- 
tices which are completely at odds with our customary taxonomic 
procedure. Their naming places a heavy burden on our nomenclature. 
To arrive at a satisfactory solution for these difficulties it is necessary 
to recognize that in many species and subspecies of ants no narrow 
distinction for color can be laid down. Since the color varies we must 
expand our concept of the 'typical' condition to include all the color 
phases. In such species there is no justification for distinguishing 
between the 'typical' coloration and off-colored conditions merely 
because the type series happened to include only a part of the color 
range. We must, in short, synonymize many of our color variants 



CREIGHTON: ANTS OF NOBTH AMEEICA 15 

with the 'typical' forms from which they should never have been 
separated. With this in mind I have relegated more than one hundred 
varieties to the synonymy in this volume. 

In the case of our subspecies the situation is much better. Com- 
paratively few of these have had to be considered as synonyms and 
in most cases revision has been upward. Most of the larger genera 
possess at least one 'protean' species to which many subspecies have 
been assigned. The structural differences which distinguish these 
subspecies usually consist of relatively minor variations in sculpture, 
pilosity and proportion which do not depart to any great extent from 
the structural criteria on which the species has been founded. The 
magnitude of these subspecific distinctions is usually very similar, 
hence if structure alone is considered, they would all have to be placed 
in the same category. On the basis of distributional data, however, 
they fall into two distinctly different groups. In many cases two or 
more of these 'subspecies' will occupy an identical range and preserve 
their distinctive structural features throughout this range without 
intergradation. Since this behavior is that of a species and not that 
of a geographical race, such variants show that they are the 'sibling 
species' with which modern taxonomy has been so vitally concerned. 
It is necessary to raise this type of subspecies to full specific rank. 
The subspecies in the second group (and a very few varieties) show 
the characteristics of geographical races. Each of them occupies a 
range of its own and maintains its structural identity over that range 
except in areas of overlap with the range of another subspecies. In 
these areas of overlap intermediate forms are produced. In this case 
all that need be done is to raise the varieties to subspecific rank, for 
this category is the proper one for geographical races. 

It seems clear that the arrangement just discussed will more nearly 
meet with the exacting requirements of modern taxonomy than does 
our older system. It would also appear that it takes care of most of 
the problems involved without calling for the use of distinctions 
which are, at present, subject to speculation. I find little sympathy 
for much that passes as gospel among the more esoteric disciples of 
speciation. The taxonomist cannot be expected to evince enthusiasm 
for species which can only be distinguished by a different rate of wing 
beat or the structure of the salivary chromosomes. Such matters are, 
doubtless, of great interest to the theorist who, because of his detach- 
ment from the practical side of taxonomy, is free to speculate as he 
pleases concerning specific criteria. But the taxonomist enjoys no 
such freedom. Unless he can furnish specific criteria which are reason- 
ably obvious and easy to use, his entire system falls into disrepute. 
It is plain, therefore, that the taxonomist will continue to pin his 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



marks the reawakening of interest in ant taxonomy. This renaissance 
was primarily a European phenomenon but its effects on the classifi- 
cation of our native ants were very considerable. In Europe, as in 
America, the first half of the nineteenth century was marked by an 
apathy toward taxonomic study. During that period, Losana and 
Westwood had each contributed a few species and Lund and Leach 
had swelled the total of unrecognizable forms, but in 1845 formicid 
taxonomy was essentially as Latreille and Fabricius had left it forty 
years before. Once the interest in the field was aroused, however, the 
pendulum swung to the opposite extreme. In the years immediately 
following 1845 no less than eight European workers began publishing 
on ant taxonomy. Of these eight men we need consider only three 
here: Julius Roger, a physician who held the Post of Public Health 
and Anatomy in the small town of Rauden in Upper Silesia, Gustav 
Mayr, a professor in the University of Brunn and Frederick Smith, 
who for some years was an assistant in the Zoological Department 
of the British Museum. 

It is easy to fall into the error of thinking that, because there had 
been few ants described at that period, the "good old days" of myrme- 
cology were marked by a delightful simplicity which made taxonomy 
much easier than at present. With most of the world teeming with 
undescribed species and the literature limited to two or three dozen 
publications there is something to be said for this view. But such 
roseate retrospections fail to consider the difficulties which resulted 
from the total lack of what we now regard as the basic generic structure 
of ant taxonomy. Without exception the older authors had made use 
of collective genera as well as collective species. Instead of our well- 
defined present day genera they had left a number of conglomerate 
groups any one of which would have furnished (as most of them have) 
material for half a dozen modern genera. Successful work under these 
circumstances demanded great acumen in dealing with generic delimi- 
tations. Both Roger and Mayr possessed this characteristic to a 
high degree but it was one of the many desirable taxonomic qualifica- 
tions which Frederick Smith lacked. 

When Smith began his studies on the ants in the collection of the 
British Museum, he enjoyed an opportunity which has seldom if 
ever been equaled. Not only was the collection wonderfully rich in 
undescribed species and genera but it contained the Banks collection 
of Fabrician types. Frederick Smith was by very long odds in a posi- 
tion which any myrmecologist might have regarded with justifiable 
envy. For more than twenty years Smith published on this material, 
during which time he described several hundred species and not a 
few genera. It is safe to say that not more than a third of these could 



CREIGHTON: ANTS OF NORTH AMERICA iy 

be recognized from his descriptions. For Smith possessed what Wheeler 
has called a "deficient classificatory sense" and few of the species 
which he described had a structure sufficiently distinct to show 
through the verbal camouflage with which he obscured them. In 
addition, Smith had little regard for what other workers in the field 
had done, hence he frequently made synonyms. It may be said that 
he showed no partiality here for as often as not he redescribed his own 
species under new specific names. The effect of these faulty practices 
on Smith's contemporaries may be easily imagined. I happen to 
know that Julius Roger found them intolerable, for I own the copy 
of the 1858 Catalogue which Smith inscribed and sent to Roger in the 
following year. This volume is interleaved and copiously annotated 
in Roger's microscopic script. On almost every page Roger has noted 
one or more corrections and some of these are made with obvious 
acerbity. It must have been particularly annoying to Roger, who 
was striving to modernize the genera of Latreille and Fabricius, to 
watch Smith's placid disregard of Fabrician species. Smith rede- 
scribed most of them under new names and in one instance (Solenopsis 
geminata) repeated the error four times. A good deal of Roger's 
taxonomic work was taken up correcting Smith's mistakes and he 
thus became the first of several investigators who were forced to labor 
at this uncongenial task. Forel, with his characteristic impetuosity, 
once published a statement that neither Smith's descriptions nor his 
types could be depended upon. But while Forel's annoyance is 
understandable, he obviously overshot the mark. It is only because 
of Smith's types, or rather because of the fact that many of them were 
preserved in the collection of the British Museum, that Smith's work 
was saved from oblivion. In 1894 Mayr visited the British Museum 
and examined Smith's material. He was able to rectify many errors 
and later, through the efforts of Emery, others were eliminated. I 
such circuitous ways many of Smith's species have been made recog- 
nizable to other workers in the field but there still remains a large 
residue whose exact nature will probably never be known. 

In contrast to the reprehensible work of Smith, that of Mayr is 
the cornerstone on which our present day taxonomy has been reared. 
Mayr began his studies of ants at an early age, publishing his first 
paper when only twenty-one years old. Thereafter he continued to 
publish on myrmecological topics for more than fifty years. Thus 
it happened that while in his youth Mayr worked with Nylander, 
Roger and Smith, he later became a contemporary of Emery and 
Forel and lived to see the advent of two other notable myrmecologists, 
W. M. Wheeler and F. Santschi. It is seldom that one man can claim 
a contemporary acquaintance with so many of the major figures in 



J BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

a field. It is even less seldom that the work of one man has such a 
profound effect in shaping a field. At a time when most myrme- 
cologists were content with the few genera which they had inherited 
from their predecessors of the eighteenth century, Mayr embarked 
on a course of generic delimitation which gave us many of our most 
important present day groups. It is significant that Mayr's name 
is attached to such well known genera as Camponotus, Pogonomyrmex, 
Aphaenogaster, Tetramorium and many others. In addition Mayr 
was the first formicid taxonomist to make extensive use of dichot- 
omous keys. These keys were often presented in connection with 
work that amounted to a generic revision although, since the papers 
carried other material as well, they were not so designated. Other 
workers in the field of ant taxonomy have produced far more descrip- 
tive work than Mayr but it is certain that no one has made a more 
timely or far reaching contribution than he did. Mayr's first myrme- 
cological interests lay almost entirely within the confines of his native 
Austria. Later he extended his work to include the entire European 
ant fauna and about 1862 turned his attention to exotic species. In 
this work he was joined by Roger and, since Smith had been occupied 
with exotics for several years, most of the development of our North 
American ant taxonomy at the middle of the last century lay in the 
hands of these three men. The death of Roger in 1865 and that of 
Smith ten years later would have left Mayr in possession of the field 
if it had not been for the entrance of two very able young myrme- 
cologists, Emery and Forel. 

Both these men matched Mayr's youthful start in the field of 
myrmecology for each published his first paper dealing with ants at 
the age of twenty-one. Like Mayr the newcomers began their studies 
on local faunas and for some time then- interest in exotic species was 
slight. About 1880, however, both Emery and Forel began to publish 
on exotic ants. As Mayr was already well embarked on this work, 
it may be seen that the period from 1880 to 1900 was one of rapid 
expansion in ant taxonomy. Each paper of any size carried descrip- 
tions of dozens of new species and it is a tribute to the skill of all 
three men that comparatively few synonyms were made. 

I wish at this point to discuss the parallelism which is said to have 
marked the lives of Emery and Forel. This concept was developed 
by Forel who, on the occasion of Emery's death in 1925, published 
an account of the similarities between Emery and himself. Most of 
these are of little consequence and Forel's preoccupation with them 
may be considered the foible of a failing septuagenarian who was 
approaching the end of his own life. But recurring throughout the 
recital is the theme of parallel activity or identical practice in the 



CREIGHTON: ANTS OF NOETH AMERICA 21 

field of myrmecology. It is this part of Forel's statement that needs 
elucidation, since it does not follow that because two men work 
together in the same field their methods or attitudes must be the 
same. Actually there was a highly significant difference in the way 
in which the two men treated ant taxonomy. 

Forel received his formal training in medicine. Thereafter he did 
postgraduate work in neural anatomy and psychiatry. In 1879 he 
was appointed as the Director and physician in charge of the Cantonal 
Asylum at Burgholzi, Switzerland. Few people would deny that he 
was a genius. Not only was he an acknowledged authority in myrme- 
cology and psychiatry but he was equally at home when practicing 
hypnotism or proselyting for prohibition. He possessed an abounding 
and infectious enthusiasm which even his severest critics found hard 
to resist. In his work with ants he was a superb observer in the field 
and keenly aware of the importance of ecological data as an aid to 
the structural distinctions of taxonomy. He clearly derived great 
pleasure from describing new species and genera of ants and did so 
with ability and distinction. His knowledge of what other taxono- 
mists had done was excellent and among the great number of new 
ants which he described comparatively few were synonyms. But 
Forel clearly felt that the important function of taxonomy was the 
description of new forms. The character of his publications leaves 
no room for doubt on this point. Although he could turn out beauti- 
fully coordinated faunal studies and had many excellent opportunities 
to do so, he rarely produced this type of work. Despite their titles, 
many of his faunal studies, for example his formicid section of the 
Histoire physique, naturelle et politique de Madagascar, or that of the 
Biologia Centrali- Americana, are little more than vehicles for carrying 
the descriptions of new species. In both these large and important 
papers previously described species are listed with bibliographic 
citations only and neither work makes any attempt to furnish keys 
which would aid in a faunal study. Their value in such work is, 
therefore, limited almost entirely to those species which were first 
described in the two publications. It must not be thought that Forel 
was unaware of the characteristics of the species which he neglected. 
He knew them well, but he clearly regarded the organizational aspects 
of taxonomy as boring routine. It appears that he never published 
a generic monograph, certainly not one of any size. He was fond of 
publishing miscellanies in which a single paper carried descriptions 
of new ants from widely scattered parts of the world, a circumstance 
which made coordination impossible. Forel was proud of his species 
and genera and bitterly resented criticism of them. For the person 
who called one of these species in question struck at what Forel felt 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



was the heart of his work. And this work was of truly heroic propor- 
tions, since during his life Forel described three thousand new ants. 
But it is correct to state that this enormous mass of description was 
his major contribution to ant taxonomy. 

In contrast to Forel, Carlo Emery was far less spectacular. In 1881 
he was appointed Professor of Zoology in the University of Bologna 
and held this position until his retirement many years later. In his 
work on ant taxonomy Emery was thorough and methodical to a 
fault. He published many faunal studies, most of which are exten- 
sively keyed and provided with data on the previously described 
species as well as the new ones. He monographed several large and 
difficult genera with exceptional care. His view of taxonomy was 
always inclusive. A new species was of little significance unless it 
could be seen in relation to the others in the genus. His ability for 
specific and generic description was equal to that of Forel and the 
care that he put into the organization of his taxonomy was incom- 
parably greater. Emery's work was so exact that he made even fewer 
synonyms than Forel, but he always welcomed the opportunity to 
correct such errors, and more often than not was the first to call 
attention to the mistake. He never lost sight of the fact that the 
description of a new species is only the beginning of taxonomy and 
no amount of comparison or difficulty in keying was too arduous for 
Emery if it permitted an easier recognition of the species involved. 
During his life Emery described almost as many new species as did 
Forel, but it is clear that he regarded this feat as less important than 
the taxonomic organization which accompanied it. 

We may count ourselves fortunate that it was Emery rather than 
Forel who undertook the first inclusive account of North American 
ants. In the three-cornered competition that developed between 
Mayr, Emery and Forel in the closing years of the last century, Emery 
had the better of it as far as material from North America was con- 
cerned. This was due in part to his association with Pergande, who 
sent Emery much of the material on which his classic Beitrage zur 
nordamerikanischen Ameisenfauna was based. With these and other 
specimens Emery was able to describe, by the year 1900, more North 
American ants than had been recognized by all other European 
myrmecologists combined. By that time he had set up about one 
hundred and eight forms coming from our region. Of the ninety or so 
remaining forms Mayr had described thirty-two, Roger twenty, Forel 
sixteen, F. Smith ten and the older authors about a dozen. It may 
be seen that by the year 1900 the contributions of European myrme- 
cologists to our ant fauna numbered about two hundred forms. 

Let us now see how our own myrmecologists fared during the period 



CREIGHTON: ANTS OF NORTH AMERICA : 

from 1845 to 1900. The record is scarcely an inspiring one for there 
is no American counterpart with which to match the activity in 
Europe during that period. In defense of our early myrmecologists 
it may be said that they worked with considerable odds against them. 
There were few adequate libraries, type material was nowhere avail- 
able and specimens sent to Europe for comparison all too frequently 
appeared as new species under the name of some European specialist. 
In 1852 Haldeman re-entered the myrmecological field with the de- 
scriptions of two new species belonging to the genus Eciton. Three 
years later Asa Fitch described six North American ants of which 
three were new forms. In 1862 Walsh described two forms of Lasius 
and in 1865 the elder Cresson gave us the description of Pogonomyrmex 
occidentalis. During the next two years there appeared from the pen 
of S. B. Buckley the descriptions of sixty-seven North American ants 
which he regarded as new species. The numerical v magnitude of this 
contribution is apparent when it is considered that prior to Buckley's 
effort there had been less than half that many species described on this 
side of the Atlantic. Buckley's collection was not only much larger 
than any previously studied by an American taxonomist but it was 
made up of material coming from widely separated parts of the 
country. As State Geologist of Texas Buckley had collected a number 
of ants from the central portion of that state. These Texas specimens 
made up slightly more than half the collection. The remaining speci- 
mens had been taken by Buckley at Washington, D. C. and Naples, 
N. Y., or had been given him by Norton. Most of Norton's material 
came from Connecticut but there were also specimens from Florida 
and California. In addition Norton had turned over to Buckley a 
series of identified European ants for purposes of comparison. Buckley 
worked up his ant collection in Philadelphia, where he had the refer- 
ence facilities to be found in the personal library of Dr. Le Conte as 
well as those in the libraries of the Philadelphia Academy of Natural 
Sciences and the Philadelphia Entomological Society. I mention these 
details because it is easy to get the impression from some of Buckley's 
critics that his work was done in complete ignorance of the subject 
he was investigating. On the contrary, Buckley seems to have been 
fortunate in having at his disposal considerably more facilities for 
research than were usually available at that time. Indeed it is hard 
to see how his situation could have been materially improved unless 
he had undertaken a trip to Europe to consult type specimens. His 
chances for producing what might have been a monumental contribu- 
tion to our ant taxonomy were excellent. What he actually did was 
to write a treatise that is best regarded as a myrmecological curiosity. 
It seems scarcely believable that with his obvious interest in the 



: BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

insects which he was describing, an interest that his severest critics 
have never denied, Buckley should have failed to produce a single 
description which permits the positive recognition of any of his species. 
In the majority of cases it is quite impossible to determine to what 
genera the insects belong, for Buckley's descriptive ineptitude was 
equalled by his extraordinary lack of regard for generic distinction. 
It should be borne in mind that by 1867 Mayr and Roger had de- 
limited most of our common genera, but even if we excuse Buckley's 
disregard of these men's work it is impossible to condone a neglect of 
previous authors which extends to Linnaeus. Buckley actually de- 
scribed as new, a species which he called Myrmica rubra. Since 
Linnaeus' species is described and figured in Latreille's Histoire 
Naturellf des Fourmis, a volume which Buckley had borrowed from 
LeConte's library, it seems reasonably clear that this same volume 
must have been gathering dust while Buckley penned the description 
of his homonym. Buckley's shortcomings have been variously attrib- 
uted to lack of training, the difficulties of the subject and innate 
perverseness. I believe that there is a much simpler explanation. 
Buckley modeled his descriptions upon those of Frederick Smith. 
This much would be obvious from a comparison of the works of the 
two men even if we did not have Buckley's published statement that 
he was strongly influenced by his English contemporary. Buckley's 
choice of a mentor was a fatal one for his work. Unlike Smith he left 
no types by which his species might have been checked. Thus the 
sole factor which saved Smith's species was lacking in Buckley's case. 
That all of Buckley's species have not been thrown into the discard 
is due to the fact that in a few instances he included field data with 
his descriptions, which identified the insect well enough to permit 
Mayr, Emery and Wheeler to surmise what it was. Even so only 
ten of his forms survive. In this ignominious fashion ended the first 
major attempt at formicid taxonomy on this side of the Atlantic. 
Very little additional work was done in this country in the years 
immediately following Buckley's fiasco. In 1868 Norton published 
the description of Eciton sumichrasti and four years later Cresson 
described two other species in the same genus. Between the years 
1879 and 1881 McCook added a handful of new forms, while Pro- 
vancher, in 1887, published several descriptions of Canadian ants. 
About 1893 Pergande began a series of studies dealing with North 
American ants. Much of Pergande's material was from Mexico but 
he described at least nine forms from areas in the United States. 
Pergande was a competent worker who knew the literature and en- 
joyed the respect and cooperation of his European contemporaries. 
When Forel visited the United States in 1899 he made a special trip 



CBEIGHTON: ANTS OP NOETH AMERICA 

to Washington to make Pergande's acquaintance. The quality of 
Pergande's descriptions was superior, but his most important con- 
tribution to ant taxonomy in this country was indirectly made. 
As has already been mentioned he sent numerous specimens to Emery. 
It was Pergande's practice to divide each series sent into two halves, 
one of which he retained. When Emery made his half the basis for 
a new species, Pergande had authentic material, if not type material, 
of that same species in his possession. There was thus built up a 
valuable nucleus of specimens whose authenticity could not be ques- 
tioned. These, with Pergande's own types, constituted the first sig- 
nificant ant collection in this country. It is to be regretted that 
Pergande's work with ants was of such short duration. He published 
little after 1895, in which year the second and final portion of Emery's 
Beitrtige appeared. 

To summarize the above, it is apparent that at the close of the last 
century the great preponderance of work on the taxonomy of North 
American ants had been done by Europeans. Their descriptions out- 
numbered those of our native myrmecologists more than two to one. 
The disparity was made much greater by the fact that of the hundred 
or so descriptions contributed by our workers more than sixty were 
wholly worthless. Authentic material was extremely scarce, and the 
majority of it was confined to the small collection made by Pergande. 
Despite Pergande's valuable work the taxonomy of North American 
ants was largely a European monopoly. 

I have stressed the year 1900 because it marks the appearance in 
the field of myrmecology of the man who was to bring about profound 
changes in this situation. In the fall of 1899 W. M. Wheeler accepted 
a professorship in the Department of Biology at the University of 
Texas. Wheeler's name has come to be so intimately connected with 
myrmecology that it seems strange to contemplate his novitiate in 
this field. The early hold which the science laid upon Wheeler's 
European contemporaries had not marked the initial years of his 
career. Wheeler's earlier scientific publications had embraced a con- 
siderable variety of subjects with the major stress, perhaps, on insect 
embryology. He had published studies in entomological . taxonomy 
but these had dealt with dolichopodid and empid flies. Certainly 
there was little to indicate that, during the next thirty-seven years 
of his life Wheeler would devote himself largely to the study of ants. 
Wheeler has stated that his initial interest in ants was occasioned 
when he happened to notice a number of workers of Alfa texana 
carrying leaf fragments into their nest. Seven years later this chance 
observation had come to fruition as an elaborately documented mono- 
graph of more than a hundred pages which is still, after forty years, 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



one of the best accounts of the attine ants ever published. From the 
outset of his work with ants Wheeler refused to be discouraged by the 
difficulties involved in studies of their taxonomy. Where a less ener- 
getic individual might have despaired, Wheeler persisted in his efforts 
to build up a working collection of authentically determined species. 
He corresponded extensively with Forel, Emery and Pergande, each 
of whom sent him identified specimens. The success of his work was 
such that by the end of three years he had amassed enough material 
to publish his first generic monograph, the Revision of the Ants of the 
Genus Leptothorax. This paper must have come as a profound surprise 
to Emery, Forel and Mayr, for in it they could clearly see the end of 
the supremacy which they had enjoyed in the field of North American 
ant taxonomy. The same year in which this paper appeared (1903) 
W T heeler left the University of Texas to accept a curatorship in the 
American Museum of Natural History. W 7 hile there he extended his 
interest in ant taxonomy to include various exotic groups but the 
majority of the taxonomic papers published during his curatorship 
dealt with the classification of our native species. While at Texas 
Wheeler had spent much time in the field, and in that state and in 
other parts of the southwest which he subsequently visited he col- 
lected assiduously. From this material came a large number of new 
species. In 1907 Wheeler visitedForel and was ableto secure a splendid 
series of cotypes and identified specimens which greatly facilitated 
his studies. 

In 1908 Wheeler accepted a professorship at Harvard. During the 
first eight years that he was there he published a number of important 
papers dealing with the classification of North American ants. But 
he was busying himself more and more with exotic material and the 
Mountain Ants of Western North America, which was published in 
January 1917, was the last large paper on our ants. Thereafter he 
published few articles dealing with North American species, although 
his work on exotic ants increased in volume until his death in 1937. 
The significant period of his work with our species lies, therefore, 
between 1900 and 1916. In these sixteen years he described more than 
two hundred and seventy forms, a contribution which so far surpasses 
that of any other myrmecologist as to make comparisons futile. 
Yet it may be stated that the most valuable contribution which 
WTieeler made to the* taxonomy of our ants was not in the large 
number of new species which he described. It was rather that Wheeler 
carried his taxonomy into the field and amplified structural distinc- 
tions with others relating to habits, distribution and ecology. For no 
amount of study of expatriated specimens can furnish these vital 
details and until the taxonomy of our ants was brought back to this 



.o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

there are two petiolar nodes or one. It is significant in this connection 
that Emery, despite the fact that he regarded the first gastric segment 
of most ponerines as the postpetiole, always included this segment 
when he spoke of the gaster of these insects. Since there is such 
excellent agreement as to what the term gaster implies in the case 
of ants, this fact may be put to good use in dealing with the above 
difficulty. In the overwhelming majority of the ponerines the gaster 
is different from that of most other ants; thus the subfamily may be 
separated on the basis of gastric structure without any chance for 
confusion since under this plan it is not necessary to mention the 
pedicel at all. This plan has been followed in the key below and I 
have also used this same character to bring out our representatives 
of the Cerapachyinae. I am aware that this distinction will not apply 
uniformly in that subfamily nor will the characters which have been 
used to separate the Cerapachyinae from the Ponerinae. But, since 
the Cerapachyinae are transitional in so many respects it seemed 
best to avoid doubtful generalizations and treat our few represen- 
tatives in a way which puts certainty of recognition in first place. 

The key which follows will apply only to the worker and female. 
In it, as in other keys presented elsewhere in this volume, no attempt 
has been made to deal with the male caste. There is reason to believe 
that at present there is no altogether satisfactory method for handling 
male ants if they are dissociated from the worker and female. Dr. 
M. R. Smith, who recently published an exhaustive monograph (1943) 
dealing with generic and subgeneric characters of male ants, was at 
pains to point out certain difficulties inherent in such an attempt. 
The structure of the male is often remarkably inconstant and this 
variability requires extensive qualification in the case of key char- 
acters. By the time these have been whittled down to care for all 
the possible exceptions there is usually not much left of them. If I 
understand Dr. Smith correctly, the generic habitus of most male 
ants is an extremely subtle matter and one which 'often defies accurate 
description'. It seems plain enough that the ordinary dichotomous 
key is not sufficiently flexible to handle these subtleties and that one 
might do as well or better with unkeyed illustrations as a guide to 
generic habitus in the male. At least this is the method followed in 
the present volume. The majority of the plates which have been 
prepared to show generic characteristics carry a figure of the male. 
Those who prefer to work with keys are referred to Dr. Smith's 1943 
monograph, which is by far the best presentation of this subject that 
has yet appeared. 



CEEIGHTON: ANTS OF NORTH AMERICA 

Key to the Subfamilies 

1. Gaster with a distinct constriction between the first and second segments 
or, if this constriction is faint, the mandibles are linear and the petiole is 

produced into a conical dorsal spine 2 

Gaster without any constriction between the first and second segments . . 3 

2. Antennal scape short and very stout, even at the base, the scape flattened 
throughout or with a greatly enlarged tip which bears a prominent lateral 

furrow for the reception of the funiculus Cerapachyinae 

Antennal scape not as above, usually long and slender, but if short and 
enlarged at the tip, at least the basal third of the scale is slender . . Ponerinae 

3. Abdominal pedicel consisting of two segments 4 

Abdominal pedicel consisting of one segment 6 

4. Frontal carinae narrow and not expanded laterally so that the antennal 

insertions are fully exposed when the head is viewed from above 5 

Frontal carinae expanded laterally so that they partially or wholly cover 
the antennal insertions when the head is viewed from above . . Myrmicinae 

5. Eyes very large, suboval or reniform and consisting of several hundred fine 

ommatidia Pseudomyrminae 

Eyes vestigial or absent, if present consisting of a single ocellus-like 
structure Dorylinae 

6. Cloacal orifice distinctly circular and usually surrounded by a fringe of 

hairs Formicinae 

Cloacal orifice slit-like, the hairs, when present, not forming an encircling 
fringe Dolichoderinae 



Subfamily PONERINAE 

The subfamily Ponerinae is regarded as a very primitive group of 
ants. This is apparent both in their structure and habits. Although 
there are ponerine genera in which certain features are highly special- 
ized, their general structure has undergone very little evolutionary 
advance. Throughout most of the subfamily the worker caste shows 
a condition of primary monomorphism. The worker closely approaches 
the female in size and there is no tendency toward the production of 
medias or minors in the worker caste. The habits of these ants show 
a comparable lack of specialization. The group is uniformly carnivor- 
ous. The workers collect other insects or small arthropods and these 
are cut to pieces and fed directly to the larvae. Regurgitation seems 
to play a much smaller part in the life of the colony than is the case 
in the higher subfamilies. The nest-founding reactions of the ponerine 
female are also primitive. During the rearing of the first brood she 
leaves the nest tj forage for food and it is presumed that she does not 
utilize salivary secretions to feed the larvae. There would seem to be 
no morphological reason why she might not do so, for Haskins and 



30 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Enzmann have shown (1938) that in many ponerine genera the wing 
muscles of the female degenerate after deflation as is the case in the 
higher subfamilies. 

While the representatives of some ponerine genera are very aggressive 
and pugnacious none of the species which occur in the United States 
show these traits. In general they are inoffensive or even timid ants 
which form small colonies and exhibit few spectacular characteristics. 
Except for Stigmatomma, which is more abundant in the northern 
part of the country than in the south, all the other genera clearly 
belong to the southern component of our ant fauna. This is true 
even in the case of Ponera for, although one species of this genus has 
a range which reaches New England and southern Canada, its primary 
representation is in areas further south. The only part of the United 
States in which ponerine ants are found in any degree of abundance 
is the region bordering the Gulf of Mexico and the Mexican boundary. 
Even in this region the incidence notably increases from north to 
south. The two areas which support the greatest ponerine population 
are southern Florida and the Brownsville region in southwestern 
Texas. In the northern half of the United States these insects make 
up a very minor and inconspicuous part of our ant fauna. 



Key to the Genera of the Subfamily Ponerinae 

1. Gaster without a distinct constriction between the first and second 
segments; node of the petiole forming a conical spine above; mandibles 
linear and inserted near the midline of the head; antennal fossae bounded 
in the rear by a rounded ridge which runs diagonally inward from the 

eye Odontomachus 

Gaster with a distinct constriction or groove between the first and second 
segments; node of the petiole blunt or rounded above; mandibles inserted 
at the sides of the head; antennal fossae not bounded in the rear by a 
diagonal ridge 2 

2. Anterior border of the clypeus denticulate; mandibles with a row of coarse, 

bidenticulate teeth Stigmatomma 

Anterior border of the clypeus variously shaped but never denticulate; 
mandibular teeth, when present, single 3 

3. Thoracic dorsum without sutures, at most a shallow impression at the 
point at which the suture should be, usually not even an impression 

present 4 

Thoracic dorsum with at least the promesonotal suture present, and 
usually the mesoepinotal suture present as well 6 

4. Apex of the gaster directed ventrally or anteroventrally when the major 
axis of the gaster is in line with that of the thorax; head and thorax 
punctato-granulose or punctato-rugose, gaster smooth with numerous 
piligerous punctures 5 



CREIGHTON: ANTS OF NORTH AMERICA ol 

Apex of the gaster directed to the rear when the major axis of the gaster 
is in line with that of the thorax; head, thorax and gaster covered with 

even, straight, longitudinal rugae Ectatomma 

5 Petiole scalelike, the front and rear faces flattened; anterior border of the 

clypeus not projecting in the middle Proceratium 

Petiole nodiform, low and much rounded above; clypeus with a narrow 
median lobe which projects strongly beyond the rest of the anterior 
border Sysphmcta 

6. Tarsal claws distinctly pectinate; mandibles without distinct teeth 

Leptogenys 

Tarsal claws simple; mandibular teeth usually distinct 7 

7. Cheek with a distinct carina extending from the eye to the clypeus 

Neoponera 

Q 

Cheek without a carina 

8. Pronotum marginate on either side Pachycondyla 

Pronotum not marginate on either side 9 

9. Thoracic dorsum with only the promesonotal suture present; clypeus flat, 
the suture which separates it from the front of the head indistinct 

Platythyrea 

Thoracic dorsum with both the promesonotal and mesoepinotal sutures 
present; clypeus with a projecting median lobe, the suture which separates 

the clypeus from the front of the head clearly distinct 10 

10. Tibia of the middle and hind legs with a single spur Ponera 

Tibia of the middle and hind legs with two spurs, the smaller lateral spur 
often obscure Euponera 

The difference in the tibial spurs used to separate Ponera and 
Euponera is often difficult to utilize because of the small size of the 
lateral spur. For practical purposes the three groups involved are 
more easily separated as follows : 

1. Middle tibiae with stiff hairs on the extensor surfaces; eyes small, the 
facets indistinct Euponera Subgenus Trachymesopus 

2. Middle tibiae without stiff hairs on their extensor surfaces; eyes of moderate 
size, their facets very distinct Euponera Subgenus Brachyponera 

3. Middle tibiae without stiff hairs on their extensor surfaces; eyes small, 
their facets indistinct Ponera 



Genus STIGMATOMMA Roger 
(Plate 1, figures 1 L 5) 

The primitive and wide-spread genus Stigmatomma is represented 
in North America by a single species, S. pallipes. The habits of this 
interesting insect have been repeatedly studied, the latest and most 
inclusive account being that of Haskins (1928 et seq.). Haskins has 



04 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

3. STIGMATOMMA PALLIPES OKEGONENSE Wheeler 

Stigmatomma pallipes subsp. oregonense Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 34, p. 389 (1915) 9 9 ; Creighton, Amer. Mus. Novitates, No. 1079, 

p. 7 (1940) 9 9 . 
Type loc: worker, Marion County, Oregon; female, Olympia, Washington. 

Types: A.M.N.H., M.C.Z. 
Range: low elevations in the coastal mountains of Oregon, Washington and 

British Columbia. 



4. STIGMATOMMA PALLIPES SUBTERRANEA Creighton 

Stigmatomma pallipes subsp. subterranea Creighton, Amer. Mus. Novitates, 

No. 1079, p. 8 (1940) 9 9 . 
Type loo: Elmo, Kansas. Type: A.M.N.H. Paratypes: M.C.Z., Coll. W. S. 

Creighton. 
Range: known only from type material. 



Genus PLATYTHYREA Roger 
(Plate 2, figures 1-3) 

The tropicopolitan genus Platythyrea has a single representative, 
P. punctata, which occurs in the southern United States. The records 
for this species indicate that it is confined to the southern tip of 
Florida and the area immediately around Brownsville, Texas. P. punc- 
tata is not likely to be confused with any of our other ponerines. In 
addition to its characteristic thoracic structure (see key) it has, when 
fully mature, a peculiar greyish black color and a dull, mattelike 
surface which give it a very distinctive appearance. 

The habits of punctata have been observed by Forel in Barbados 
(1899), Wheeler in the Bahamas (1905) and M. R. Smith in Puerto 
Rico (1936). The insect prefers to nest in old stumps or logs or under 
the bark of trees in shady situations. The workers are active and 
forage singly. The colonies are small consisting of from fifty to two 
hundred individuals. It is both carnivorous and predatory. 



1. PLATYTHYREA PUNCTATA (F. Smith) 

Pachycondyla punctata F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 108 (1858) <f . 

Platythyrea punctata Roger, Berl. Ent. Zeitschr., Vol. 7, p. 173 (1863); Forel, 
Rev. Suisse Zool., Vol. 9, p. 335 (1901); M. R. Smith, Amer. Mid. Natu- 
ralist, Vol. 37, No. 3, p. 533, pi. 3, fig. 9 (1947) 9 . 

Platythyrea inconspicua Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 961 
(1870) 9 ; Emery, Ann. Soc. Ent. Fr. (6), Vol. 10, p. 56 (1890) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA 6L 

Typeloc: San Domingo. Type: British Museum. 

Range: southern Florida and southwestern Texas and southward through the 
Antilles and Central America. 



Genus ECTATOMMA F. Smith 

The genus Ectatomma is represented in America north of Mexico 
by a single species, E. (Parectatomma) hartmani. This insect is very 
imperfectly known. It was described by Wheeler in 1915 from one 
worker which was taken at Huntsville, Texas. There are no additional 
records to show that it has been found again. In contrast to our lack 
of knowledge concerning hartmani there is a large and entertaining 
body of literature dealing with the behaviour of E. tuberculatum in 
Texas. This is the famous "kelep", whose introduction into the 
United States was attempted in the hope that the ant would control 
the ravages of the cotton-boll weevil. The introduction of tuberculatum 
into Victoria County, Texas in 1904 was given a great deal of pub- 
licity. It is not surprising that when Wheeler expressed doubts as 
to the ability of the insect to acclimatize itself he was taken to task 
for his views. The most vociferous champion of the "kelep" was 
Dr. O. F. Cook, who published several reports dealing with the habits 
of tuberculatum (1904 et seq.). The zeal which Dr. Cook exhibited in 
defense of the "kelep" appears to have been considerably greater 
than his knowledge of myrmecology. He was very soon in serious 
difficulty with Wheeler. The latter had little patience with Cook's 
"Corybantic enthusiasm" and less for his peculiar interpretation of 
facts. The exchange of opinion between the two men was continued 
over a period of two years. Dr. Cook held up manfully under a very 
heavy fire but was presently faced with the uncomfortable realization 
that tuberculatum was not becoming acclimatized, precisely as Wheeler 
had predicted. This put an end to Cook's publications on the "kelep" 
and terminated an unusually bizarre episode in myrmecological 
literature. 



Subgenus PARECTATOMMA Emery 

1. ECTATOMMA (PARECTATOMMA) HARTMANI Wheeler 

Ectatomma (Parectatomma) hartmani Wheeler, Bull. Amer. Mus. Nat. Hist., 
Vol. 34, p. 390 (1915) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 
No. 3, p. 535 (1947) 9 . 

Type loc: Huntsville, Texas. Type: M.C.Z. 

Range: known only from the single type. 



do BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

There has been considerable confusion in regard to this species and 
much of this is undoubtedly due to the fact that it is known only from 
a single type specimen. I have ventured to propose an altogether 
different method of treatment for hartmani from that employed by 
Dr. M. R. Smith in 1947. Dr. Smith utilized the presence of bifid 
tarsal claws as the separatory character for the genus Ectatomma. 
I believe that he is mistaken in supposing that this character holds 
throughout the genus. I have not examined the type of hartmani 
since Dr. Smith's 1947 generic monograph appeared, hence I cannot 
state that the claws of hartmani are simple. I feel sure, however, that 
this is the case for this condition is regularly encountered in the 
closely related subgenus Gnamptogenys. While I have utilized the 
lack of distinct sutures on the thoracic dorsum of hartmani as a means 
for separation, there is an even simpler method of recognition. The 
beautifully regular longitudinal rugae which cover all parts of this 
insect distinguish it clearly from any other North American species. 



Genus PROCERATIUM Roger 
(Plate 3, figures 1-4) 

Up to the present time only five representatives of the genus 
Proceratium have been described from North America. With so few 
forms involved the chance for taxonomic confusion ought to be slight. 
It is somewhat disconcerting, therefore, to discover that only one of 
these five forms, P. croceum, is easily and certainly recognizable. The 
remaining four have become involved in an intricate taxonomic tangle, 
for which there seems to be no altogether satisfactory solution at 
present. 

In 1863 Roger set up the genus Proceratium to include his new 
North American species silaceum as well as his older croceum, which 
he had earlier placed in the genus Ponera. The differences which 
separate these two species are very distinct and little difficulty would 
have resulted if Roger's plan had been followed. But the matter was 
put in a very different light when Emery described a third species, 
crassicorne, thirty years later. In preparing his Beitrage Emery 
studied specimens of croceum and silaceum which Roger had sent to 
him. Whether these were types is not clear. Emery speaks of them 
as 'original examples'. But at least it is certain that Roger had iden- 
tified these specimens and if they were not types they had been com- 
pared with type material. The specimen of silaceum was imperfect, 
the abdomen and petiole having been broken off, but Emery was 
able to remedy this defect, since he had three workers referable to 



CREIGHTON: ANTS OF NORTH AMERICA 6t 

silaceum. These specimens, which Pergande had sent him, came from 
Beatty, Pennsylvania. Emery also had a single female of silaceum 
which had been loaned him by Mayr. 

On the basis of these five specimens Emery redescribed silaceum 
and confirmed the wide differences which separate that species from 
croceum. But Emery was not content to let the matter rest, for he 
had two additional specimens which he was not willing to fit into 
Roger's scheme. Both these specimens had been taken by Pergande 
in or near Washington, D. C. According to Emery, these two speci- 
mens were slightly smaller than silaceum (2.33 mm. against 2.75 mm. 
for silaceum) and had a lower petiolar node and thicker antennae, 
with the joints of the scape, except the last, all much wider than those 
of silaceum. As a result Emery considered these specimens as repre- 
senting a new species, which he called crassicorne and, since one of 
his specimens was a little more hairy than the other, he made the 
hairier one the type of the variety vestitum. Before he did so, however, 
Emery secured a statement from Pergande that all of the specimens 
which he had collected in the type locality of vestitum (Charlton 
Heights, Md.) were also hairy. This was the situation in 1915 when 
Wheeler, on the basis of five specimens, added the subspecies rugulosum 
to silaceum. In making his comparison Wheeler had what appears 
to be a part of the nest series from Beatty, Pennsylvania, which Emery 
had used in his redescription of silaceum. Wheeler regarded these 
four specimens from Beatty as cotypes of silaceum (which they cer- 
tainly are not) and marked them with a cotype label. As far as I 
know, they are still so marked, although when I examined them in 
1938 they had been placed with material identified as vestitum. 

I have no wish to seem unduly harsh in evaluating the above work. 
P. silaceum is never an abundant ant and other myrmecologists as 
well as Emery and Wheeler have been forced to deal with limited 
amounts of material. Yet it is not unreasonable to claim that neither 
Emery nor Wheeler exercised the caution which the circumstances 
demanded. Emery had seen only seven specimens, W'heeler only nine. 
Neither man had a field acquaintance with the insects they were 
studying. It is not surprising, therefore, to find that each of the 
three new forms which they set up is highly suspect. In my opinion, 
crassicorne, rugulosum and vestitum are all synonyms of silaceum. 
In the following paragraphs I have presented the reasons on which 
this opinion is based. 

In past years I have taken many colonies of Proceratium in various 
stations in the southeastern United States. In the majority of these 
colonies there were workers whose golden yellow color marked them 
as callows. While they had not attained the rich, chestnut brown 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



color of the mature worker these callows were active in the colony, 
since their integument had become hard. It is evident that the 
worker of Proceratium colors slowly, even for a ponerine, and that 
most colonies will contain a considerable number of light-colored 
workers during the spring and summer months. While Proceratium 
shows a certain flexibility in nest sites, it clearly prefers to nest in 
'red rotten' logs. In such situations the color of the punky wood 
blends remarkably with that of the fully colored workers. The golden 
yellow workers, on the other hand are very conspicuous. For this 
reason they are sometimes the only specimens secured. This circum- 
stance has undoubtedly contributed to the confusion which surrounds 
silaceum. 

When such golden yellow individuals are examined under a micro- 
scope much more light is reflected than is the case with the fully 
colored workers. This glare largely obliterates certain details of surface 
sculpture. This is particularly true of the rugose-reticulate sculpture 
on the head which may, in strong lights, be scarcely visible. I believe 
that this is due to the fact that the rugae are nearly transparent in 
the yellow specimens and that they do not cast shadows as they do 
when they become darker. It may further be noted that the extent 
to which the body hairs are erected usually bears a close correlation 
to the degree of coloration in the worker. In the golden yellow speci- 
mens many of the body hairs are reclinate or appressed. As the color 
deepens more and more hairs become erect. Since the hairs also 
darken with age, it is easy to get the impression that the fully colored 
worker is much more pilose than the callow. 

In my opinion, the above facts will explain the recognition of the 
variety vestitum and the subspecies rugulosum. The first was said to 
be a more hairy and more coarsely punctured version of crassicorne. 
The second differed from silaceum only in its darker color and heavier 
sculpture. But Emery's recognition of crassicorne cannot be explained 
on this basis. As already noted, crassicorne was supposedly distin- 
guished from silaceum by its slightly smaller size, its lower and thicker 
petiolar node and its thicker funicular joints. There is very little 
reason to put much faith in the matter of size difference. Since Emery 
had only one specimen of crassicorne and four workers of silaceum, he 
could scarcely have been expected to realize that the size range in 
most nest series of silaceum embraces the size of crassicorne also. The 
difference in the width of the funicular joints is also of less significance 
than might be supposed. According to Emery the last funicular joint 
of silaceum is the same length as the preceding four joints taken 
together, while that of crassicorne is distinctly longer than the pre- 
ceding four joints taken together. Emery's figures do not bear this 



CREIGHTON: ANTS OF NORTH AMERICA 6V 

out for, if allowance is made for the fact that the funiculus of silaceum 
is figured as strongly curved, the proportion of the terminal joint to 
the preceding four is almost identical in both species. The same 
consideration applies to the structure of the petiolar nodes. Emery's 
figure of silaceum is drawn with the node of the petiole close to the 
declivious face of the epinotum. In his figure of crassicorne the node 
is sloped away from the declivious face of the epinotum. This gives 
the impression that the node of crassicorne is lower than that of 
silaceum. If the figure of crassicorne is enlarged to the size of that of 
silaceum and the angle of the petiole altered to conform with that of 
the latter insect, the two figures are practically identical when super- 
imposed. In this case Emery seems to have been the victim of an 
optical delusion which resulted from the position in which he drew 
the petiole of crassicorne. 

It is interesting to note that most myrmecologists have avoided any 
mention of crassicorne unless it was absolutely necessary to do so. 
The only attempt to deal with this species in any detail appears to be 
that published by the Wessons in 1940. According to these investi- 
gators the nests of crassicorne show a contrast to those of silaceum, 
since crassicorne nests both in rotten wood and in the soil while 
silaceum nests only in rotten wood. I cannot attach much significance 
to this distinction for, if I understand the matter correctly, the speci- 
mens which the Wessons discovered in soil seem to have been strays. 
The only clearly established nest of crassicorne which they mention 
was in all respects comparable to those of silaceum. 

Key to the species of Proceratium 

1. Length 3.75-4 mm.; node of the petiole seen in profile thick and blunt 
above, the base very little thicker than the crest; epinotal teeth prominent 

croceum 

Length 2.75 mm. or less; node of the petiole in profile slender, the base 
notably thicker than the crest; epinotal teeth very short, scarcely more 
than angles silaceum. 



1. PROCERATIUM CROCEUM (Roger) 

Ponera crocea Roger, Berl. Ent. Zeitschr., Vol. 4, p. 288 (1860) 9 . 
Sysphingta crocea Mayr, Sitzungsb. Akad. Wiss. Wien., Vol. 53, p. 501 (1866) 9 . 
Proceratium croceum, Mayr, Verh. Zool- bot. Ges. Wien, Vol. 36, p. 437 (1886); 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 264, pi. 8, figs. 5, 6 (1895) V 9 ; 

M. R. Smith, Ann. Ent. Soc. Amer., Vol. 23, p. 390, figs. 1-3 (1930) < 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 532, pi. 2, fig. 6 

(1947) 9. 



U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: 'the state of Carolina'. Types: none in this country. 
Range: Gulf Coast region from eastern Texas to Florida and sporadically 
north to latitude 38. 

2. PROCERATIUM SILACEUM Roger 

Proceratium silaceum Roger, Berl. Ent. Zeitschr., Vol. 7, p. 172 (1863) 9 ; 
Emery, Zool. Jahrb. Syst., Vol. 8, p. 265, pi. 8, figs. 7, 8 (1895) 9 9 ; 
Emery, Bull. Soc. Ent. Fr., p. 101, fig. 2 (1896) 9 ; Kennedy & Talbot, 
Proc. Indiana Acad. Sci., Vol. 48, p. 202, figs. 1-7 (1939) 9 9 <?. 

P. silaceum subsp. rugulosum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
p. 390 (1915) 9 9 . 

P. crassicorne Emery, Zool. Jahrb. Syst., Vol. 8, p. 265, pi. 8, figs. 9, 9a (1895) 9 . 

P. crassicorne var. vestitum Emery, Ibid., p. 266 (1895) 9 . 

Type loc: 'North America'. Types: none in this country. 

Range: most of the United States east of the Mississippi River except southern 
Florida, northern New York and New England. This insect has also been 
taken in southern Ontario by Dr. Kennedy. These Canadian records 
(Pelee Island and vicinity) are, however, no further north than others 
from Pennsylvania and southern New York. 



Genus DYSPHINCTA Roger 
(Plate 4, figures 1-2) 

For most students of North American Formicidae the genus Sys- 
phincta is exemplified by the extraordinary gastric configuration found 
in S. pergandei. In this species the dorsum of the first gastric segment 
is greatly expanded and strongly curved. As a result the posterior edge 
of this segment actually lies at the middle of the lower surface of the 
gaster. The whole posterior half of the gaster consists of the rounded 
dorsum of the first segment. The remaining gastric segments form a 
conical projection which points forward and downward from the middle 
of the gaster. While all the members of the genus Sysphincta possess 
a gaster in which the tip is reflected, the degree of curvature is seldom 
so extreme. In some of the species, among them melina, the reflected 
gastric tip appears to be tucked under the posterior end of the gaster, 
a condition very similar to that which occurs in the related genus 
Proceratium. For this reason Sysphincta is best separated from 
Proceratium by using Emery's criteria of the angular, projecting 
median lobe of the clypeus and the feebly incrassate antennal scapes. 
In Proceratium the clypeus lacks the angular, projecting, median lobe 
and the antennal scapes are notably thickened at the tips. 

The rarity of the two species which represent the genus Sysphincta 
in North America has become a myrmecological by-word. In the case 



CREIGHTON: ANTS OF NOKTH AMERICA 



of S. melina there is nothing to controvert such a view. During more 
than eighty years since its description by Roger it has been taken once. 
A different situation marks our knowledge of pergandei. While the 
number of specimens in collections is small the locality records of this 
handful of material present a rather surprising picture. S. pergandei 
has now been taken in nine eastern states and its known range extends 
from southern New York to northern Alabama and Mississippi. At 
present the recorded western limit of the range is central Ohio. In 
view of this rather extensive range it seems clear that the rarity of 
pergandei is not an outcome of restricted distribution. Perhaps it 
would be more correct to say that pergandei is a very elusive ant rather 
than a very rare one. 

The data concerning the nesting habits of pergandei is fragmentary 
and contradictory. In 1905 Wheeler cited the fieldwork of Schmitt 
who found this insect under large stones in damp meadows. This 
observation has been repeated by people whose own findings negate 
it. There is equally good, if not better, evidence to show that pergandei 
nests on rocky hillsides where the cover is dense. There is reason for 
believing that the insect is subterranean in habit but its feeding re- 
sponses have not been ascertained with certainty. A very suggestive 
approach to this last problem has been made by L. G. and R. G. 
Wesson (1940), who had the good fortune to secure a single colony of 
pergandei and keep it under observation. This nest consisted of a 
queen, eleven workers and eight males. Since it was found in close 
proximity to a nest of Camponotus castaneus the artificial nest was 
made to include both colonies. The castaneus workers were excluded 
from the chamber housing the pergandei colony but the latter could 
enter the chamber containing the castaneus workers and brood. The 
results failed to show any special relationship between the two species. 
On the other hand the members of the pergandei colony soon began 
to attack and kill each other. As this is usually an index of faulty 
environmental conditions one is tempted to wonder if the enforced 
proximity to the castaneus colony may not have produced this result. 
Attempts to feed the pergandei colony with various sorts of living and 
dead insects also gave negative results for the most part. The only 
insect food which the workers were observed to accept consisted of 
the gasters of formicine ants. On the basis of these studies the Wessons 
suggest that pergandei may feed upon dead or dying ants. 

Key to the species of Sysphincta 

1. Anterior portion of the petiole depressed, the posterior portion forming a 
low but distinct scale; reflected dorsum of the gastric segment not strongly 
projecting to the rear and forming an even curve with the reflected tip; 



42 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

length 3.5 mm melina 

Petiole evenly convex above, the anterior portion not depressed; reflected 
dorsum of the gastric segment strongly projecting to the rear so that the 
reflected tip appears to arise from the mid-ventral surface of the gaster; 
length 4.0 mm pergandei 

1. SYSPHINCTA MELINA (Roger) 

Ponera melina Roger, Berl. Ent. Zeitschr., Vol. 4, p. 291 (1860) 9 9 c?. 
Proceratium melinum Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 438 (1886). 
S. melina Emery, Zool. Jahrb. Syst., Vol. 8, p. 263, pi. 8, figs. 1-3 (1895) 9 9 d 1 . 
Type loc: "Carolina". Types: none in this country. 

Range: known only from the type material and a few other specimens taken 
by Schmitt in Pennsylvania. 

2. SYSPHINCTA PERGANDEI Emery 

Sysphincta pergandei Emery, Zool. Jahrb. Syst., Vol. 8, p. 264, pi. 8, fig. 4 

(1895) 9 ; Emery, Bull. Soc. Ent. Fr., p. 101, fig. 1 (1896) 9 ; Emery, 

Genera Insectorum, Fasc. 118, pi. 2, fig. 6 (1911) 9 ; M. R. Smith, Ent. 

News, Vol. 39, p. 242 (1928) &; M. R. Smith, Amer. Mid. Naturalist, 

Vol. 37, No. 3, p. 532, pi. 2, fig. 7 (1947) 9 . 
Type loc: "Pennsylvania and District of Columbia". Types: none in this 

country. 
Range: eastern United States. Southern New York to northern Alabama and 

Mississippi and west to Ohio. Most of the records appear to come from 

hilly or mountainous areas. 



Genus NEOPONERA Emery 
(Plate 5, figures 1-4) 

Neoponera is a New World genus with most of the species occurring 
in Central America and tropical South America. The number of 
species which range northward into Mexico is small and of these only 
one, N. mllosa, reaches southwestern Texas. The insect which Forel 
described in 1901 as Neoponera agilis was said to have been taken in 
California but this has been generally regarded as an error in the 
locality. It is possible that the locality referred to some region in 
Lower California but it is very unlikely that aailis occurs within our 
borders. These insects frequently reach our ports in shipments of 
tropical fruit, etc., but they do not appear to be able to establish 
themselves after introduction. The endemic N. mllosa is, therefore, 
the only member of the genus which need be considered. 



CREIGHTOX: ANTS OF NORTH AMERICA 4d 

1. NEOPONERA VILLOSA (Fabricius) 

Formica villosa Fabricius, Syst. Piez., p. 409 (1804) 9 . 

Ponera villosa Illiger, Mag. Insectenk., Vol. 6, p. 194 (1807) 9 ; Roger, Berl. 

Ent. Zeitschr., Vol. 5, p. 1 (1861) 9 . 
Pachycondyla villosa Mayr, Verb. Zool-bot. Ges. Wien, Vol. 12, p. 720 (1862); 

Mayr, Sitzungsb. Acad. Wiss. Wien, Vol. 61, p. 397 (1870) 9 ; Emery, Ann. 

Soc. Ent. Fr. (6), Vol. 10, p. 74 (1890) 9 ; Forel, Biol. Cent. Amer., 

Vol. 3, p. 14 (1899). 
Neoponera villosa Emery, Ann. Soo. Ent. Belg., Vol. 45, p. 47 (1901); Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 47 (1901) 9 9 cf; M. R. Smith, 

Amer. Mid. Naturalist, Vol. 37, No. 3, p. 536, pi. 3, fig. 11 (1947) 9 . 
Ponera bicolor Gue"rin, Icon. Regne Anim., Vol. 7, Ins. p. 242 (1845) 9 . 
Ponera pilosa F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 95 (1858) cf. 
Ponera peduncvlata F. Smith, Ibid., p. 96, pi. 6, fig. 25 (1858) 9 . 
Type loc: "Meridional America". Types: none in this country. 
Range: southwestern Texas through Mexico and Central America and as far 

south in South America as Paraguay. In Texas this insect appears to be 

mainly confined to a region extending about one hundred and fifty miles 

north of Brownsville. According to Wheeler it does not occur north of the 

latitude of San Antonio. 



Genus PACHYCONDYLA F. Smith 
(Plate 6, figures 1-4) 

This genus, like Neoponera, is mainly confined to the Neotropical 
Region. The subspecies montezumia, which belongs to the widely 
distributed P. harpax, is the only representative of Pachycondyla in 
the United States. This subspecies occurs in southern Texas. The 
entire range of montezumia extends through Mexico and into Central 
America. Thereafter it is replaced by the typical harpax, whose range 
extends as far south as Paraguay. The records for monlezumia coming 
from Texas lie principally in a triangular area marked by Houston on 
the east, San Antonio on the west and Brownsville on the south. 
There is less certainty than might be wished as to the eastern limit 
of this range. Wheeler has published a Louisiana record for monte- 
zumia but the scarcity of records east of Houston make this appear 
exceptional. 

The habits of montezumia were described in a paper which Wheeler 
published in 1900. The insect constructs small, irregular nests in the 
soil under stones and logs. The workers avoid direct sunlight, foraging 
early in the morning and keeping in the shade as much as possible. 
They feed upon other insects and myriapods. 



44 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

1. PACHYCONDYLA HARP AX MONTEZUMIA F. Smith 

Pachycondyla montezumia F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 108 

(1858) 9 d". 
Pachycondyla harpax subsp. montezumia Forel, Biol. Cent. Amer., Vol. 3, 

p. 12 (1899) 9 . 
Pachycondyla harpax Wheeler, Biol. Bull., Vol. 2, p. 4-6, fig. 2, 3, 8 (1900) 

9 9 d"; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 401 (1908) 

9 9 (?; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 537, pi. 

2, fig. 8 (1947) 9 . 

Ponera amplinoda Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 171 (1866) 9 . 
Pachycondyla orizaba Norton, Amer. Naturalist, Vol. 2, p. 8 (1868) 9 . 
Type loc: Mexico. Type: Brit. Mus. 
Range: south central and southwestern Texas through Mexico to Central 

America. 



Genus EUPONERA Forel 
(Plate 7, figures 1-4) 

The genus Euponera is represented in America north of Mexico by 
three species but of these three only one, giliia, is clearly endemic to 
this region. Of the other two species there can be no question that 
solitaria has been imported. The situation is by no means so clear in 
the case of stigma. This insect occurs widely in tropical America both 
in the Antilles and on the continent. Its presence in southern Florida 
may indicate a range which extends southward through Cuba, par- 
ticularly as it is by no means rare in that island. On the other hand 
although stigma occurs in Mexico, there are, apparently, no records 
from southern Texas. Since there are several ponerine genera whose 
ranges reach the Brownsville area of Texas from Mexico but which 
lack representatives in Florida, the reversal of the usual situation in 
the case of stigma may be an indication that it has been introduced 
into Florida. The writer inclines to this belief but at present too 
little is known about the Florida representatives to permit a positive 
statement in this regard. 

The habits of the three species differ only in minor details. They 
all prefer to nest in moist, dead logs or stumps. It is interesting to 
note, however, that stigma and solitaria will occasionally nest in moist 
soil under stones, whereas gilva very rarely, if ever, does so. The 
latter species is also more fussy about the position of its nest in the 
log, preferring to nest in the loose frass under the bark. The size of 
the colonies varies from a few dozen to several hundred individuals. 
In the latter case, several dealated queens are usually present. The 
writer has never seen solitaria in the field but in the other two species 



CEEIGHTON: ANTS OF NORTH AMERICA 4o 

the workers are rather sluggish and surprisingly difficult to see when 
they are foraging. For this reason the collector is seldom aware of the 
presence of a colony until he has broken into the nest. For a detailed 
account of the nest activities of giha the reader is referred to a paper 
published by Haskins in 1931. 

The key which follows is essentially that presented by M. R. Smith 
in his 1934 publication on our species of Euponera. 



Key to the species of Euponera 

1. Mesonotum surrounded by .a distinctly impressed suture, its dorsum 
blisterlike and rather sharply set off from the pronotum; tibiae of the 
middle legs long and without stiff hairs on their extensor surfaces; eyes of 

moderate size, their facets distinct (Subgenus Brachyponera) solitaria 

The suture which surrounds the mesonotum only moderately impressed, 
dorsum of the mesonotum not strongly convex and not sharply set off from 
the pronotum; tibiae of the middle legs short and bearing stiff hairs on 
their extensor surfaces; eyes small, their facets indistinct (Subgenus 
Trachymesopus) 2 

2. Length 3-3.4 mm.; color light to dark ferrugineous; the antennal scape 
failing to reach the median occipital border by an amount which exceeds 

its greatest thickness; mesopleurae not distinctly striated gilva 

Length 4.5-4.8 mm.; color very dark brown to black; the antennal scape 
reaching the median occipital border; mesopleurae distinctly striated .... 

stigma 



Subgenus BRACHYPONERA Emery 

1. EUPONERA (BRACHYPONERA) SOLITARIA (F. Smith) 
(Introduced) 

Ponera solitaria F. Smith, Trans. Ent. Soc. Lond., p. 404 (1874) 9 ; Forel, 

Mitt. Schweiz Ent. Ges., Vol. 10, p. 267 (1900) 9 9 . 
E. (Brachyponera) solitaria Emery, Ann. Soc. Ent. Belg., Vol. 45, p. 47 (1901); 

Emery, Deutsche Ent. Zeitschr., p. 366, fig. 6 (1909) 9 9 ; Wheeler, Bull. 

Amer. Mus. Nat. Hist., Vol. 22, p. 306, pi. 41, fig. 13 (1906) 9 ; M. R. 

Smith, Ann. Soc. Ent. Amer., Vol. 27, No. 4, p. 559, fig. 1 (1934) 9 ; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 539, pi. 3, fig. 12 

(1947) 9. 

Type loc: Hiogo, Japan. Types: British Museum. 
Range: (in the United States) Georgia to Virginia. 

This species is endemic to Japan and parts of China. It appears to 
be well established in one or two areas in the Central Atlantic States. 



_8 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Subgenus TRACHYMESOPUS Emery 

2. EUPONEEA (TKACHTMESOPUS) GILVA (Roger) 

Ponera gilva Roger, Berl. Ent. Zeitschr., Vol. 7, p. 170 (1863) 9 ; Emery, Zool. 

Jahrb. Syst., Vol. 8, p. 266, pi. 18, fig. 10 (1895) 9 . 
Pachycondyla (Pseudoponera) gilva Emery, Ann. Soc. Ent. Belg., Vol. 45, p. 46 

(1901) 9. 
Euponera (Trachymesopus) gilva Emery, Genera Inseotorum, Ponerinae, p. 86 

(1910); Wheeler and Gaige, Psyche, Vol. 27, p. 69 (1920) 9 ; Creighton 

and Tulloch, Psyche, Vol. 37, p. 71, fig. 1-3 (1930) 9 9 rf; M. R. Smith, 

Ann. Ent. Soc. Amer., Vol. 27, p. 561 (1934) 9 ; M. R. Smith, Amer. 

Mid. Naturalist, Vol. 37, No. 3, p. 539, pi. 4, fig. 13 (1947) 9 . 
Euponera (Trachymesopus) gilva subsp. harnedi M. R. Smith, Ann. Ent. Soc. 

Amer., Vol. 22, p. 543 (1929) 9 . 

Type loc: "North America". Types: none in this country. 
Range: southeastern States. At present published records are confined to 

Mississippi, Alabama and Tennessee but it seems certain that gilva also 
occurs in northwestern Florida and southern Georgia. 



3. EUPONERA (TRACHYMESOPUS) STIGMA (Fabricius) 
(Introduced?) 

Formica stigma Fabricius, Syst. Piez., p. 400 (1804) 9 . 

Ponera stigma Roger, Verz. Formic., p. 16 (1863); Emery, Ann. Mus. Civ. 

Genova, Vol. 25, p. 434 (1887) 9 . 
Ponera quadridentata Roger, Berl. Ent. Zeitschr., Vol. 4, p. 285 (1860) 9 ; 

F. Smith, Jour. Proc. Linn. Soc. Zool., Vol. 3, p. 143 (1858) 9. 
Ponera americana Mayr, Verh. Zool-bot. Ges. Wien, Vol. 13, p. 722 (1862) 9 . 
Pachycondyla (Pseudoponera) stigma Emery, Ann. Soc. Ent. Belg., Vol. 45, 

p. 46 (1901). 
Euponera (Pseudoponera) stigma Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 398 

(1901); Rev. Suisse Zool., Vol. 9, p. 339 (1901). 
Euponera (Trachymesopus) stigma Emery, Genera Insectorum, Ponerinae, 

p. 85 (1910) ; M. R. Smith, Ann. Ent. Soc. Amer., Vol. 27, p. 563 (1934) 9 . 
Type loc: "Meridional America". Types: none in this country. 
Range: widely distributed throughout the Antilles and the tropical portions 

of North and South America. The records from the United States are 

confined to southern Florida. 



Genus PONERA Latreille 
(Plate 8, figures 1-4) 

The ants which belong to the genus Ponera present a singularly 
uniform group as far as their habits are concerned. All of them form 



CREIGHTON: ANTS OF NORTH AMERICA 4 

small and rather obscure colonies in rotten wood or soil. They are 
decidedly timid ants and rarely forage on the surface. As far as is 
known, all the species feed on insects or other small arthropods. Their 
distribution is, on the other hand, considerably more interesting. Of 
the six species which occur in the United States, two range far to the 
south. Thus opaciceps has been taken in Uruguay, and trigona subsp. 
opacior in Chile. Both these species are widely distributed in Central 
and South America and the Antilles. Two other species, erpatandria 
and inexorata, are known to occur as far to the south as Costa Rica 
and one of these (ergatandria) is also Antillean. Of the remaining two 
species oblongiceps is known only from type material, hence its range 
is a matter of conjecture but coarctata subsp. pennsyhanica does not 
enter the tropics at all as far as is known. On the contrary, in the 
southern portion of its range its numbers show a marked decrease. 
Because of this it has been customary to accord a different faunal 
relationship to coarctata, allying it to the boreal element of our ant 
fauna rather than to the Neotropical group. But if one considers the 
extraordinary distribution of coarctata, this interpretation is less 
certain. The typical coarctata occurs in Europe where it is largely 
confined to the Mediterranean basin. There is, however, a subspecies 
boerorum from Natal and another, mackayensis, from Queensland. 
About all that one can say under such circumstances is that pennsyl- 
vanica, unlike some of the other species of the genus, shows no tendency 
to utilize the tropical areas to the south of its range. 

The genus Ponera possesses a number of species in which the only 
known male is a wingless individual known as an ergataner. In most 
respects these so strongly resemble the worker that a rather close 
inspection is necessary to distinguish the two. The ergataner, in ad- 
dition to possessing male copulatory organs, is usually a little larger 
than the worker and sometimes has one more joint in the antennae. 
Very little is known about the mating of such species, although it is 
generally assumed that, because of the aptery of the ergataner, it must 
be between individuals from the same nest. 

The North American representatives of the genus Ponera were 
monographed in 1936 by M. R. Smith. He subsequently described 
our sixth species, oblongiceps. The key below has been expanded to 
include that species. Otherwise it is as given in Dr. Smith's monograph. 



Key to the species of Ponera 

1. External border of the mandibles sinuate; base of the epinotum laterally 

compressed; color ferrugineous yellow inexorata 

External border of the mandibles not sinuate 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

2. Petiole when viewed in lateral profile slender, subtriangular (that is 
narrower dorsally than ventrally) body slender; color varying from light 

brown to pitch black trigona subsp. opacior 

Petiole when viewed in lateral profile robust, subrectangular (that is ap- 
proximately as wide dorsally as ventrally) 3 

3. Head very finely punctate, shining; eyes extremely small (3-4 facets); color 

light brownish yellow or dirty brownish yellow; size 2.3-2.9 mm 4 

Head with coarser punctures, therefore subopaque or opaque; eyes with 
more than 3-4 facets; color normally brownish black or black; robust; size 
exceeding 3 mm 5 

4. Antennae of the male (ergataner) twelve-jointed; pubescence distinct but 

fine ergaiandria 

Antennae of the male (ergataner) thirteen-jointed; pubescence coarser. . . 

oblongiceps 

5. Head with dense, coarse punctures, subopaque 

coarctata subsp. pennsylvanica 

Head densely but more finely punctate, thus giving the general surface a 
subopaque appearance, but lacking the coarse granular effect common to 
pennsylvanica opaciceps 



1 . PONEBA COARCTATA PENNSTLVANICA Buckley 

Ponera pennsylvanica Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 171 (1866) 9 . 
Ponera coarctata subsp. pennsylvanica Emery, Zool. Jahrb. Syst., Vol. 8, p. 267 

(1895) 9 9 cT; Wheeler, Biol. Bull., Vol. 2, p. 44, figs. 1-4 (1900) 9 9 cT; 

M. R. Smith, Ann. Ent. Soc. Amer., Vol. 29, p. 426 (1936) 9 9 ; M. R. 

Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 538, pi. 4, fig. 14 (1947) 9 . 
Type loc: Pennsylvania. Types: none known to exist. 
Range: eastern United States and Canada. 

According to Smith, the range of this insect does not extend west 
of the 97th degree of longitude. It is most abundant in the north- 
eastern states, the frequency in Canada and the Gulf States being 
notably less than that in the middle of the range. 



2. PONERA ERGATANDEIA Forel 

Ponera ergatandria Forel, Trans. Ent. Soc. Lond., p. 365 (1893) 9 9 cf ; 

Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 405 (1908) 9 9 c?; 

M. R. Smith, Ann. Soc. Ent. Amer., Vol. 29, p. 425 (1936) 9 9 cf . 
Type loc: Island of St. Vincent, B. W. I. Types: none in this country. 
Range: in the United States, Texas and Florida only. Presumably does not 

occur in the central Gulf States. 



CREIGHTON: ANTS OF NORTH AMERICA <\) 

3. PONERA INEXORATA Wheeler 

Ponera inexorata Wheeler, Psyche, Vol. 10, p. 94, fig. 2 (1903) 9 9 ; M. R. 

Smith, Ann. Ent. Soc. Amer., Vol. 29, p. 422 (1936) 9 9 . 
Type loe: Austin, Texas. Types: M.C.Z. 
Range: in the United States, sporadically distributed in the southern part of 

the country from Texas eastward to the Carolinas. 

By present designation the type series is restricted to the specimens 
coming from Austin, Texas. Wheeler's original description was based 
on these specimens as well as others coming from San Angelo and Ft. 
Davis. Elsewhere in this volume I have shown why such restriction 
is necessary. 



4. PONERA OBLONGICEPS M. R. Smith 

Ponera oblongiceps M. R. Smith, Proc. Ent. Soc. Wash., Vol. 41, No. 3, figs 

1-3 (1939) 9 9 rf 1 . 

Type loc: Priest Bridge, Maryland. Types: U.S.N.M. 
Range: known from type material only. 



5. PONERA OPACICEPS Mayr 

Ponera opaciceps Mayr, Verb. Zool-bot. Ges. Wien, Vol. 37, p. 536 (1887) 9 9 ; 

M. R. Smith, Ann. Ent. Soc. Amer., Vol. 22, p. 545 (1929) rf 1 ; M. R. 

Smith, Ann. Ent. Soc. Amer., Vol. 29, p. 428 (1936) 9 9 <?. 
Type loc: Province of Sta. Catharina, Brazil. Types: none in this country. 
Range: in the United States, southern and southwestern states as far west as 

Arizona. In the east the insect does not occur north of South Carolina. 

In the west it has been taken in northern Colorado. 



6. PONERA TRIGONA OPACIOR Porel 

Ponera trigona var. opacior Forel, Trans. Ent. Soc. Lond., p. 363 (1893) 9 9 ; 
Emery, Zool. Jahrb. Syst., Vol. 8, p. 268 (1895) 9 9 cf; Emery, Mem. 
[. Sc. Bologna, (5), Vol. 5, p. 296 (1895) tf; M. R. Smith, Ann. Ent. 
Soc. Amer., Vol. 29, p. 423 (1936) 9 9 . 

Type loc: Island of St. Vincent, B. W. I. Types: none in this country. 

Range: in the United States, extensively distributed in the southern and 
southwestern states. It has been taken as far north as Ohio and as far 
west as Oregon but these records are exceptional. The normal northern 
boundary of its range appears to be about the latitude of southern Virginia. 
It is scarce west of Texas. 



oil BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Genus LEPTOGENYS Roger 

Subgenus LoBOPELTA Mayr 
(Plate 9, figures 1-4) 

The distribution of L. (Lobopeltd) elongata, the only species of 
Leptogenys which occurs in the United States, is an interesting one. 
Several of the older records published for elongata have tended to 
obscure the distributional characteristics of this species. Some of the 
older records are highly suspect. Records for elongata have been re- 
ported from Colorado, the District of Columbia and Maryland. It is 
unlikely, but not impossible, that elongata occurs in southeastern 
Colorado. But the records from the District of Columbia and Mary- 
land seem plainly impossible. After Wheeler's studies of the habits of 
elongata in 1900 and 1904, the prevalence of this species in central 
Texas was clearly established. But the older records persisted and to 
them were added others scarcely more trustworthy. As late as 1923, 
Wheeler published the statement that the range of elongata extends 
from Texas to Georgia. I have been unable to discover the basis on 
which this statement rests. I have never seen any specimens of 
elongata coming from Georgia and it seems unlikely that the insect 
occurs there. For many years Dr. M. R. Smith made a very careful 
study of the ants of Mississippi and for several summers the writer 
engaged in intensive field work on ants in Alabama. If the range of 
elongata extends from Texas to Georgia it is reasonable to expect that 
it would occur in both of the states just mentioned. W T hile the insect 
is rather sporadic, even in its area of greatest abundance, it is certainly 
not inconspicuous. It seems hard to believe that it would not have 
been taken in Alabama or Mississippi if it occurs in those two states. 

The matter has been further obscured by the presence of the sub- 
species manni in southern Florida. The first Florida records from 
Bellaire were originally attributed by W T heeler to the typical elongata. 
Later he set up the subspecies manni on material taken at Dunedin 
and Miami. No mention was made of the Bellaire specimens in the 
original description of manni but nine years afterwards these specimens 
were also attributed to manni. Thus during the period from 1923 to 
1932, it would have been correct, on the basis of published data, to 
assume that both elongata and manni occur in Florida. Actually, the 
two have widely separated ranges. All the evidence indicates that 
manni is restricted to southern Florida. Except for Wheeler's question- 
able Georgia record all others for the typical elongata come from 
regions west of the Mississippi River. The most eastern record to date 
seems to be Beaumont, Texas but the insect almost certainly occurs 
in Louisiana as well. 



CREIGHTON: ANTS OF NORTH AMERICA 01 

Once the above points are clearly in mind, it is possible to appreciate 
a significant characteristic in the distribution of the typical elongata. 
Unlike many of the Mexican species whose ranges run into Texas, 
elongata does not increase in abundance as one approaches the border. 
This seems clear from the excellent set of records published by Dr. 
M. R. Smith in 1936. Except for a single record from Brownsville, 
all the others were from an area north of the latitude of Matagorda. 
This area extended from Beaumont west to San Antonio and from 
Matagorda north to Waco. It would seem, therefore, that the typical 
elongata is less abundant in the Brownsville area (and presumably the 
adjacent portion of Mexico as well) than in stations further north. 
We have in elongata a northern species with the 'fringes' extending 
southward, not the reverse. In this respect it would appear to repeat, 
on a much restricted scale, the same distributional characteristics 
which mark Stigmatomma. It may also be noted that, while the 
related species mexicanum occurs in Mexico, no allied species occurs 
in Cuba. The presence of the subspecies manni in Florida would, 
therefore, seem to indicate a previous range which spanned the entire 
Gulf Coast. 

The biology o'f elongata was described in a paper which W. M. 
Wheeler published in 1900. He was able to show that winged females 
do not occur in this species. Their place in the colony is taken by the 
'gynecoid' worker, a fertile individual in which the abdomen and 
petiole are slightly larger than those of the ordinary worker. The 
rather small colonies of elongata are built in soil or in rotten logs. 
According to Wheeler this species feeds largely on wood slaters of the 
genera Armadillium and Oniscus. 



Key to the subspecies of Leptogenys (Lobopelta) elongata Buckley 

1. Petiole very distinctly truncated anteriorly; surface of the head and thorax 
only moderately shining; color light brownish or yellowish red .... elongata 
Petiole less distinctly truncated anteriorly; surface of the head and thorax 
more strongly shining; color deep red elongata subsp. manni 



1. LEPTOGENYS (LOBOPELTA) ELONGATA (Buckley) 

Ponera elongata Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 172 (1866) 9 . 

L. (Lobopelta) elongata Emery, in Wytsman Genera Insectorum, Fasc. 118, 
p. 105, pi. 3, fig. 13, b, c (1910) 9 9 d 1 ; M. R. Smith, Amer. Mid. Natu- 
ralist, Vol. 37, No. 3, p. 538, pi. 4, figs. 15, 15a (1947) 9 . 

Leptogenys elongata Wheeler, Biol. Bull., Vol. 2, p. 2, fig. 4 (1900) 9 9 cf; 
Wheeler, Ibid., Vol. 6, p. 257 (1904). 



, BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

Lobopelta septentrionalis Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 438 

(1886) 9. 

Leptogenys septentrionalis Emery, Zool. Jahrb. Syst., Vol. 8, p. 268 (1895) 9 . 
? Ponera texana Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 170 (1866) 
Type loc: Austin, Texas. Types: none known to exist. 
Range: southern Texas from the Louisiana border to Brownsville and as far 

north as the latitude of Waco. 

2. LEPTOGENYS (LOBOPELTA) ELONGATA MANNI Wheeler 

L. (Lobopelta) elongata subsp. manni Wheeler, Amer. Mus. Novitates, No. 69, 

p. 14 (1923) 9 . 

Type loc: Dunedin, Florida. Types: M.C.Z. 
Range: southern Florida. 

This subspecies was described from four workers, one taken by 
Mann at Miami and three by McGregor at Dunedin. As no type 
designation was made by Wheeler, all four of the specimens could be 
regarded as types. It is my opinion, however, that the type series 
should be restricted to the Dunedin specimens. Much confusion has 
arisen in the past from the practice of extending the type series over 
material from several stations. There is no justification for such 
practice and it weakens the position of those who contend that the 
members of a single nest series, used as the basis for the description 
of a new form, should all have equal rank as cotypes. 



Genus ODONTOMACHUS Latreille 
(Plate 10, figures 1-5) 

The extraordinary mandibular structure of Odontomachus and the 
unusual habits which are connected with them have attracted much 
attention. Perhaps for this reason certain noteworthy distributional 
features of these insects have received less study than they deserve. 
Particularly is this true of 0. haematoda, whose distribution is scarcely 
less remarkable than are its habits. In general, most Ponerine ants 
do not vary greatly within the species. It is, therefore, only occasion- 
ally that one encounters in this subfamily a species comparable to 
those protean agglomerations so common among the Myrmicinae and 
Formicinae. But 0. haematoda is the exception which proves the rule. 
This insect, with its apparently endless array of infraspecific variants, 
is in all respects as labile as the most plastic species in either of the two 
higher subfamilies. Coupled with this is a remarkable distribution 
through the Antilles and continental America. It is much to be re- 



CREIGHTON: ANTS or NORTH AMERICA oo 

gretted that so little of the range of haematoda lies within our borders, 
for it is not often that one encounters a species so rich in both insular 
and continental variants and a comparison of these should prove of 
great interest. Of the forms which occur in the United States, the 
most abundant is the subspecies insularis. This insect is widely dis- 
tributed in Florida and occurs also in southern Georgia. Dr. M. R. 
Smith, who monographed our North American forms of haematoda in 
1939, is of the opinion that it must also occur in southeastern Alabama. 
This seems entirely logical, although the writer has never been able 
to take it there or in the portion of Florida which lies between Alabama 
and the Gulf. It is almost certainly not endemic to the eastern Gulf 
States, although it may have been brought into some of the ports 
there. This curious failure of insularis to range westward along the 
Gulf from Florida rather strongly suggests that it has come into 
Florida from Cuba. There it is widespread and by no means rare. A 
similar failure to occupy the region along the Gulf Coast marks the 
western subspecies clarus. The range of this insect lies in southwestern 
Texas, whence it extends southward into Mexico. There appear to be 
no records of clarus from eastern Texas, although there is a single 
notable record from Louisiana published in Dr. Smith's monograph. 
Whatever the significance of this record may be, it is certain that 
clarus, unlike insularis, is an ant of the semi-desert regions. Its 
colonies are smaller than those of insularis, rarely consisting of more 
than fifty individuals and it nests by preference in coarse gravelly soil 
with the nests fully exposed to the sun. Much the same consider- 
ations apply to the two subspecies known to occur in southern Arizona. 
Both form small colonies, usually under stones, in coarse, gravelly soil. 
But the subspecies desertorum nests at lower elevations than does the 
subspecies coninodis, which rarely comes below elevations of 5000 feet 
in the canyons of the southern Arizona mountains. The two are, 
therefore, restricted to separate ranges although the stations in which 
they occur may lie within a few miles of each other. Since the sub- 
species clarus occurs in Mexico, the geographical affinity of the Texas 
specimens seems clear enough. They must be regarded as coming from 
the northern portion of a range which extends into northeastern 
Mexico. The relationship of the other two subspecies is less clear but 
there is good reason to believe that they are also northern fringes of 
variants whose main range lies to the south of the border. It seems 
likely that when more material is available from northern Mexico, 
particularly from that virtually unworked region south of the Big 
Bend area, that all three of these subspecies can be related to others 
which occur further south in Mexico. For it is clear that if we are to 
find intergrades between the subspecies, we must look for them in the 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



tropical portions of continental America. The insular variants are too 
well isolated in most cases to permit intergradation, as are the scattered 
representatives which occur within our borders. Even though we know 
less about the relationship of the various forms than might be wished, 
one thing seems to be certain. In the case of haematoda we have a 
species which has entered the United States from the south along two 
distinct routes. Moreover, the eastern and western representatives 
have remained widely separated, although there would seem to be no 
particular obstacle to the western spread of insularis along the Gulf 
Coast. This curious situation offers engaging possibilities to those 
interested in speciation and geographical distribution. 

The classical account of the habits of haematoda is that which was 
published by W. M. Wheeler in 1900. This widely quoted study was 
based upon field observations and also upon the examination of 
colonies in artificial nests. As a result, Wheeler was able to clear up 
several points which had puzzled earlier students, who had access only 
to cabinet specimens. Wheeler showed that the long hairs, which arise 
between the bases of the mandibles and point forward, act as triggers 
when the mandibles are open. When these hairs are touched the 
mandibles snap shut. As to what happens next depends largely upon 
what the mandibles close on. If the object closed on is small and not 
too hard it is usually cut in two, very much as a wire is cut by side- 
cutting pliers. Small insects which fall afoul of Odontomachus are, 
therefore, apt to have their appendages cut away in short order. But 
if the object closed upon is too large to be included in the grasp of 
the closing jaws and, more particularly, if it is hard enough to let the 
tips of the jaws slide over it, the ant is thrown through a series of 
backward somersaults by the force of its closing mandibles. In either 
case there is a distinct click produced when the jaws snap shut. 
Wheeler claimed that the insects always land on their feet 'like a cat' 
at the end of the leap but this is not invariably the case. They do, 
however, get on their feet as soon as they land and, since the leap is 
too rapid for the eye to follow easily, unless one is looking directly at 
them as they land, it is easy to get the impression that they land right- 
side-up. A further point in Wheeler's account has made for misunder- 
standing. He fed his captive colonies on flies, which were promptly 
dismembered and ultimately cut to pieces. He compared the attack 
of the Odontomachus workers to that of hungry dogs and gave a vivid 
picture of the celerity with which the victim was dispatched. Out of 
this appears to have grown a popular belief that Odontomachus is 
an exceptionally ferocious ant. The writer has seen several accounts, 
intended for general reading, that were little short of hair-raising. 
Certainly no one who has studied this insect in the field would subscribe 



CREIGHTON: ANTS OF NORTH AMERICA ;x 

to any such view. The colonies of insularis, clarus and coninodis which 
the writer has found have been much more interested in scrambling 
to safety than in defending the nest. I would regard haematoda as a 
rather timid ant. It may be admitted that when these ants attack 
other insects the results are spectacular but this is due to their peculiar 
mandibular structure and not a result of inherent savagery. 

The key presented below is essentially that given by Dr. M. R. 
Smith in his 1939 monograph. 

Key to the subspecies of Odontomachus haematoda Linne 

1. Posterior third or more of the prothoracic disc with distinct longitudinal 

striae; color ranging from brown to deep, brownish black insularis 

Posterior third of the prothoracic disc with distinct transverse striae; color 
lighter, pale yellowish brown to dark reddish brown 2 

2. Petiolar node conical, without a well-marked spine; color pale yellowish 

brown coninodis 

Petiolar node with a distinct, acuminate spine ; color reddish brown 3 

3. Length 9-10 mm. ; color very dark reddish brown; head of the larger workers 
with distinct posterior ocellar pits, usually with an erect hair near each 

pit desertorum. 

Length 7-8 mm.; color light reddish brown; posterior ocellar pits indistinct 
or absent clarus 



1. ODONTOMACHUS HAEMATODA CLARUS Roger 

O clarus Roger, Berl. Ent. Zeitschr., Vol. 5, p. 81 (1861) 9 ; Forel, Ann. Soc. 

Ent. Belg., Vol. 45, p. 124 (1901) 9 ; Wheeler, Bull. Amer. Mus. Nat. 

Hist., Vol. 24, p. 407 (1908) 9 9 rf. 
O. haematoda subsp. clarus Emery, in Wytsman Genera Insectorum, Fasc. 118, 

p. 115 (1910); M. R. Smith, Jour. N. Y. Ent. Soc., Vol. 47, p. 129 (1939) 9 . 
0. texanus Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 335 (1867) 9 . 
O. haematodes Wheeler, Biol. Bull., Vol. 2, p. 2, figs. 1, 5, 6 (1900). 
Type loc: Texas. Types: none in this country. 
Range: southwestern Texas and northeastern Mexico. 



2. ODONTOMACHUS HAEMATODA CONINODIS Wheeler 

O. haematoda subsp. coninodis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
p. 391 (1915) 9 9 ; M. R. Smith, Jour. N. Y. Ent. Soc., Vol. 47, p. 128 
(1939) 9. 

Type loc: Miller and Ramsey Canyons, Huachuca Mountains, Arizona. 

Types: M.C.Z., Coll. W. S. Creighton. 

Range: known only from the type locality. 



u6 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

3. ODONTOMACHUS HAEMATODA DESERTORUM Wheeler 

O. haematoda subsp. desertorum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
p. 391 (1915) 9 ; M. R. Smith, Jour. N. Y. Ent. Soc., Vol. 47, p. 128 
(1939) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 538, 
pi. 4, figs. 16, 16a (1947) 9 . 

Type loc: Carnegie Desert Laboratory, Tucson, Arizona. 

Types: M.C.Z. 

Range: deserts of southern Arizona. 



4. ODONTOMACHUS HAEMATODA INSULARIS Guerin 

0. insularis Guerin, Icon. Regne Animal, Ins. Vol. 7, p. 423 (1845) 9 ; Lucas, 
in Ramon Hist. Fis. Cuba, Vol. 7, p. 757, pi. 18, fig. 7 (1857) 9 9 cf . 

O. haematoda subsp. insularis Emery, Bull. Soc. Ent. Ital., Vol. 22, p. 44 (1890) ; 
M. R. Smith, Jour. N. Y. Ent. Soc., Vol. 47, p. 127 (1939) 9 . 

Type loc: Cuba. Types: none in this country. 

Range: Cuba, Florida and southern Georgia. Distributed by commerce 
through many parts of the tropics. 



Subfamily CERAPACHYINAE 

The very limited part which the Cerapachyinae play in our ant 
fauna scarcely justifies an extensive consideration of this subfamily. 
There are, however, certain features which ought to be considered, for 
the status of the Cerapachyinae is different from that of any other 
subfamily of ants. In delimiting the subfamily Cerapachyinae in 1920, 
Wheeler was forced to use a combination of characters, none of which 
are definitive in themselves. Some of these characters are shown by 
the Ponerinae, others by the Dorylinae. The recognition of the 
Cerapachyinae rests upon the fact that no other group combines these 
characters. This blending of ponerine and doryline traits had been 
recognized many years earlier by Emery and Forel but Wheeler was 
able to augment their observations by additional information con- 
cerning the structure of the larvae and the activities of the workers. 
His studies supported Emery's contentions that the cerapachyine 
genera are a link between the Ponerinae and Dorylinae. The larvae 
of the Cerapachyinae are, so far as is known, very similar to those of 
the Dorylinae. The habit of the eyeless workers of raiding the nests 
of other ants for food certainly suggests doryline affinities. The 
structure of the sexual forms is decidedly transitional. The female 
may be winged and very similar to the female of certain ponerine 
genera, or apterous and ergatoid (again a ponerine trait) or dichtha- 
diiform as in the Dorylinae. The males appear to be more uniform in 



CREIGHTON: ANTS OF NORTH AMERICA a. 

structure but still manage to combine the characteristics of the two 
other subfamilies. Their general appearance is very much like that of 
the ponerine male but they lack cerci, possess a deeply furcate sub- 
genital lamina and have retractible genital armature. These last three 
traits are rare in the ponerine male but common in the males of the 
Dorylinae. 

While Wheeler's proposal to treat the Cerapachyinae as a subfamily 
is preferable to the attempt to force this group of genera into the 
Ponerinae or Dorylinae, it by no means solves certain taxonomic 
difficulties inherent in the subfamily. Because there are no distinctive 
subfamily characteristics in the Cerapachyinae it is necessary to 
employ tribal or generic criteria for their recognition. It is interesting 
to note that in the generic key which Wheeler published in 1922, no 
attempt was made to separate the Cerapachyinae from the Ponerinae 
either in the key to the subfamilies or that of the tribesof the Ponerinae. 
While the joint key was said to be a matter of convenience it would 
be much more convenient if the Cerapachyinae possessed good sub- 
family characteristics. Until these are discovered it is not possible to 
arrive at any altogether satisfactory method for handling this difficult 
group. 

Key to the Genera of the Subfamily Cerapachyinae 

1. Antennae of eleven segments; antenna! scape not flattened; antennal fossa 
bordered laterally by a distinct carina; frontal carinae not expanded 

laterally, the antennal insertions fully exposed Cerapachys 

Antennae with twelve segments; antennal scape much flattened over its 
entire length; antennal fossa not bordered laterally by a carina; frontal 
carinae somewhat expanded laterally and largely concealing the insertions 
of the antennae ". Acanthostichus 



Genus CEEAPACHYS F. Smith 

Subgenus PARASYSCIA Emery 
(Plate 11, figures 1-2) 

The majority of the species which belong to Cerapachys are found 
in the tropics of the Old World. The two species which occur within 
our borders both belong to the subgenus Parasyscia and are both 
confined to the states of the southwest. The two species are rare and 
very little is known about their habits. Wheeler was able to make a 
few observations on the type colony of augustae, which he took at 



5s BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Austin, Texas. The nest was about six inches below the surface of soil 
containing limestone chips. In the nest were ten workers and a female. 
Wheeler was of the opinion that this represented most if not all of the 
colony. The insects crept about slowly with the antennal scapes thrust 
forward in a peculiar fashion. Wheeler inferred that these ants lead 
a subterranean existence. The fact that they are eyeless would 
certainly favor such a view. It is virtually certain that these ants are 
carnivorous and it is probable that they are predaceous. We badly 
need more information on the habits of our two species. 

1. CEEAPACHYS (PAKASYSCIA) AUGUSTAE Wheeler 

C. (Parasyscia) augustae Wheeler, Bio. Bull., Vol. 3, p. 182, figs. 1, 2 (190(2) 
V 9 ; M. R. Smith, Proc. Ent. Soc. Wash., Vol. 44, No. 4, p. 63 (1942) <?; 
M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 526, pi. 1,'fig. 3 
(1947) 9. 

Type loc: Austin, Texas. Types: M.C.Z. 

Range: western Texas to southern Arizona. 



2. CEKAPACHYS (PAKASYSC 



R. Smith 



C. (Parasyscia) davisi M. R. Smith, Proc. Ent. Soc. Wash., Vol. 44, p. 64 

(1942) d\ 

Type loc: Ft. Jeff Davis, Texas. Type and paratypes: TJ.S.N.M. 
Range: known only from type material. 

As Dr. Smith notes, the male of davisi is larger (3.8 mm.) than that 
of augustae and has the head more rounded behind. In the male of 
davisi all the segments of the antennal funiculus, except the first, are 
distinctly longer than broad. The sides of the thorax and the area 
between the inner border of the eye are delicately rugulose in davisi. 
It is to be hoped that workers and females of this interesting species 
will soon be discovered, for its exact relationship to augustae is problem- 
atical as long as the other two castes remain unknown. 



Genus AcANTHOSTICHUS Mayr 

Subgenus CTENOPYGA Ashmead 

The two North American species belonging to Acanthostichus have 
been placed in the subgenus Ctenopyga. The relationships of Cteno- 
pyga are far from clear. It was originally described as a genus by 



CHEIGHTON: ANTS OF NOETH AMERICA c 

Ashmead in 1906. It contained the single species, townsendi, based 
upon male and female specimens taken in Mexico. Later Emery made 
Ctenopyga a subgenus of Acanthostichus and added to it the species 
texanus, which Forel had described in 1904. This species was also 
described from a female. Since no additional specimens appear to 
have been taken, the characteristics of the worker remain unknown 
except as they may be inferred from the structure of the female. Emery 
believed that it is possible to separate Ctenopyga from Acanthostichus 
because the female of the first group is winged while that of the latter 
is apterous and resembles a dichthadiigyne. He may be correct in this 
contention but it seems well to point out that there is only one species 
of Acanthostichus, A. quadratus, in which the female is known. The 
others are based upon the worker or the male. It is by no means 
certain that the female of Acanthostichus is always apterous or that 
of Ctenopyga always winged. In this connection it is interesting to 
note that the female from which texanus was described lacked wings. 
Emery was evidently of the opinion that it had once possessed them 
but this is by no means certain from Forel's description. There is 
little to be gained by such speculations, however, for it is obvious that 
no satisfactory conclusion as to the relationship of Ctenopyga to 
Acanthostichus can be reached until both groups are much better 
known. 

1. ACANTHOSTICHUS (CTENOPYGA) TEXANUS Forel 

A. texanus Forel, Ann. Soc. Ent. Belg., Vol. 48, p. 168 (1904) 9 ; Wheeler, 
Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 400 (1908) 9 . 

A. (Ctenopyga) texanus M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 
p. 526, pi. 1, fig. 4 (1947) 9 . 

Typeloc: Brownsville, Texas. Types: none in this country. 

Range: known from southwestern Texas only. 



Subfamily DORYLINAE 

The ants which belong to the Subfamily Dorylinae are unique in so 
many respects that it is difficult to treat them in the same fashion as 
the members of the other subfamilies. The doryline male is so unlike 
that of most ants that for a very long while it was not recognized as 
an ant at all. This circumstance has caused an unusual amount of 
complication in the taxonomy of the group, for many of the species 
have been described from the male only and it is usually quite im- 
possible to associate such males with their proper workers unless one 
is lucky enough to find the two castes together in one colony. In 



bU BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

addition, the group possesses a most unusual type of female called a 
dichthadiigyne. This strange creature is a sort of oversized worker 
with a very voluminous gaster which on occasion becomes greatly 
distended with eggs. The dichthadiigyne has a worker type of thorax 
and never possesses wings, hence there is good reason to suppose that 
she usually mates with males of the same colony. 

These considerations, however, are not what has attracted attention 
to the doryline ants. The African 'drivers' and the New World 'army' 
ants are widely known because of their spectacular foraging habits. 
At certain seasons these insects become nomadic and the entire colony 
sets out on an expedition which becomes a series of raids against any 
animal that may happen to be in the vicinity. Since some of the species 
form large colonies and possess a large soldier caste with powerful jaws, 
the raids are not to be taken lightly, although there has been much 
exaggeration of the capacity of these insects for attacking large verte- 
brates. Undoubtedly they would do so if given the opportunity but 
unless the animal were badly crippled or comatose it could easily 
avoid the attack. The main victims of these raids are other insects 
which are secured in prodigious numbers. 

Although the raids of the dorylines have been repeatedly studied 
and described, the basis for them was not clearly understood until the 
last few years. In 1941 Schneirla began the publication of his illumi- 
nating studies on the behavior o.f Eciton colonies. Most of his studies 
have dealt with species which do not occur within the limits of the 
United States, but his work is of such importance that it may be cited 
as a model for those who care to undertake similar observations on our 
species. 

Schneirla established the fact that the Eciton colony passes through 
an alternation of statary and nomadic phases. In the statary phase 
the colony has a fixed bivouac which is often in a hollow log or tree 
trunk. From this 'nest' a certain amount of raiding goes on but this 
by no means involves the movement of the whole colony. During the 
statary period much brood is present and as the older brood approaches 
the pupal stage the raids diminish. When most of the older brood has 
pupated the raids may cease altogether. But with the emergence of 
the callows the colony becomes very active and when most of them 
have emerged another nomadic phase is inaugurated, with the colony 
moving from place to place and setting up temporary bivouacs as the 
occasion demands. The brood present in the nest at this time has 
come from eggs laid during the foregoing statary period. It should be 
clear from the above that the Eciton female has periodic bursts of egg- 
laying activity. Schneirla has shown that this is the case and that 
when the female is actively engaged in laying eggs she becomes notably 



CREIGHTON: ANTS or NORTH AMERICA 01 

physogastric, with the abdominal segments forced apart by the mass 
of eggs within. The activity of an Eciton colony can, therefore, be 
explained as due to the reproductive behavior of the female. The 
nomadic phase corresponds roughly to her period of reduced sexual 
activity. The statary phase follows after the onset of a new period of 
marked sexual activity. 

As already noted these observations have been mainly made 'upon 
tropical species of Eciton. It remains to be seen how they will apply 
to our species of Neivamyrmex. It will undoubtedly be much more 
difficult to make the requisite observations on Neivamyrmex, for they 
are very difficult insects to observe in the field. The colonies are 
seldom large and their activities are remarkably obscure. Several of 
the species appear to be largely subterranean in their habits. If one 
may judge from Schneirla's work with Eciton, however, the results 
which might be secured would amply repay the trouble they might 
entail. 

Genus EciTON Latreille 
(Plate 12, figures 1-4) 

All the representatives of Eciton which occur in the United States 
belong to the subgenus Labidus or to the subgenus Neivamyrmex. 
The workers of the two subgenera may be separated as follows : 

Key to the Subgenera of Eciton 

1. Tarsal claw with a median tooth Labidus 

Tarsal claw simple, without a median tooth Neivamyrmex 



Subgenus LABIDUS Jurine 

The subgenus Labidus is represented in the United States by three 
species, coeoum, crassicorne and esenbecki. The first insect is widely 
distributed in southern Texas. It is by no means an obscure ant and 
has frequently been observed in the field. According to Wheeler and 
Long (1901), coecum constructs brood chambers beneath stones and is 
'entirely subterranean'. This observation needs qualification for 
coecum, like many other species of Eciton, will forage above ground 
when the circumstances are suitable. In the vicinity of Austin, where 
Wheeler made most of his studies, it might be expected that coecum 
would make nocturnal or crepuscular forays. Many species of Eciton 
will avoid full sunlight whenever possible. Wheeler states (1908) that 
coecum will feed on practically anything of an edible nature but it 



tw BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

seems clear that most of the food eaten has a high protein content. 
Living and dead insects form the main part of the diet but this species 
has also been observed to feed on carrion and the kernels of various 
nuts. 

Since the male of esenbecki has never been associated with a worker, 
the following key deals only with caecum and crassicorne. 

Key to the species of Labidus (workers) 

1. Inner border of the mandible with a large, sharp, triangular, central tooth 

caecum 

Inner border of the mandible with a long, low, flattened projection at the 
middle crassicorne 

Before presenting the very extensive synonymy of coecum I wish to 
explain the arrangement followed. In most cases where a reasonably 
constant nomenclature has been followed it is possible to reduce the 
number of the citations by eliminating those which contain nothing of 
particular value to the investigator. This is not feasible in the case 
of coecum. It would be difficult to say how many references to this 
species exist in the literature. During the last century and a half it 
has been assigned to seven different genera and described under at 
least fourteen different specific names. Since the synonymy should 
contain at least one reference to each of the names employed, it follows 
that even the minimum listing will be a lengthy one. But if the list 
is presented chronologically, a number of the older references, which 
have virtually no value, are given a prominence which they do not 
merit. I have, therefore, divided the synonymy into three sections. 
In the first, in addition to, the original description, are references 
dating from 1886. In that year Mayr recognized Latreille's Formica 
coecum as an Eciton. All references in the first group, except the 
original description will, therefore, carry present-day generic and 
specific designations. The second group consists of a chronologically 
arranged list of references in which the generic name, the specific 
name, or both, may differ from present usage. Finally, there is the 
list of doubtful references which are believed to apply to coecum. For 
most purposes only the first group of references need be consulted and 
this arrangement will, I trust, save much effort. 



1. ECITON (LABIDUS) COECUM (Latreille) 

Formica coeca Latreille, Fourmis, p. 270, pi. 9, fig. 56 (1802) 9 . 
Eciton coecum Mayr, Wien Ent. Zeit., Vol. 5, p. 119 (1886) V ; Mayr, Verb. 
Zool-bot. Ges. Wien, Vol. 37, p. 553 (1887) 9 ; E. Andre, in Forel, Biol. 



CREIGHTON: ANTS OF NORTH AMERICA oo 

Central! Amer., Vol. 3, p. 160 (1900) 9 ; Emery, Mem. Accad. Sci. 

Bologna (5), Vol. 8, p. 517 (1900) 9 d" ; Wheeler & Long, Amer. Naturalist, 

Vol. 35, p. 166, fig. 2c (1901) o"; Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 24, p. 408, pi. 26, fig. 3 (1908) cf. 
E. (Labidus) caecum Emery, in Wytsman Genera Insectorum, Fasc. 102, pi. 1, 

fig. 3 (1910) 9 ; Weber, Amer. Mid. Naturalist, Vol. 26, No. 2, p. 327, 

figs. 1-6 (1941) 9 9 ; M. R. Smith, Ibid., Vol. 37, No. 3, p. 526, pi. 1, 

fig. 1 (1947) 9 . 

Labidus latreillei Jurine, Nouv. Meth. Class. Hym., p. 283 (1807) d" . 
Labidus jurinei Shuckard, Ann. Nat. Hist., Vol. 5, No. 2, p. 198 (1840) d". 
Labidus sayi Haldeman, Stansbury's Exp. Great Salt Lake, Lippincott Grambo 

& Co., p. 366 (1852). tf. 
Labidus atriceps F. Smith, Cat. Hym. Brit. Mus., Vol. 7, p. 5, pi. 2, fig. 4 

(1859) d". 

Eciton vastator F. Smith, Jour. Ent. Soc., Vol. 1, p. 71 (1860) 9 . 
Eciton erratica F. Smith, Ibid., p. 71 (1860) 9 . 
Nycteresia coeca Roger, Berl. Ent. Zeitschr., Vol. 5, p. 22 (1861) 9 . 
Myrmica rubra Buckley, Proc. Ent. Soc. Phila., p. 335 (1866) 9 . 
Pseudodichthadia incerta E. Andre, Spec. Hym. Europe, Vol. 2, Supl. p. 8, 

fig. 1-5 (1885) 9 - - 

Eciton jurinei Mayr, Wien Ent. Zeit., Vol. 5, p. 33 (1886) cf . 
Eciton omnivorum Emery, Bull. Soc. Ent. Ital., Vol. 33, p. 163 (1891) 9 ; 

Emery, Ibid., Vol. 26, p. 179, pi. 2, fig. 9 (1894) 9 9 cf. 
Mutilla (Labidus) fulvescens Blanchard in Cuvier Regne Animal Ins. (Ed. 3), 

Vol. 2, pi. 118, fig. 2 (1894) cf . 

Eciton selysi Forel, Ann. Soc. Ent. Belg., Vol. 48, p. 169 (1904) 9 . 
? Formica omnivora Olivier, Encycl. Meth. Ins., Vol. 4, p. 496 (1791) 9 . 
? Labidus pilosus F. Smith, Cat. Hym. Brit. Mus., Vol. 7, p. 7 (1859) d\ 
? Eciton smithi Dalla Torre, Wien Ent. Zeit., Vol. 21, p. 89 (1892) tf. 
Type loc: "Meridional America". Types: none in this country. 
Range: Texas south to Argentina. 



2. ECITON (LABIDUS) CRASSICOHNE F. Smith 

E. crassicorne F. Smith, Trans. Ent. Soc. Lond. (2), Vol. 3, p. 163, pi. 13, 
figs. 1, 2 (1855) 9 ; F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 151, pi. 6, 
figs. 1-4 (1858); Mayr, Novara Reise Formic., p. 77 (1865) 9 ; Mayr, 
Wien Ent. Zeit., Vol. 5, p. 115 (1885); Emery, Bull. Soc. Ent. Ital., 
Vol. 26, p. 179, pi. 2, fig. 8 (1894) 9 ; Forel, Biol. Central! Amer. Hym., 
Vol. 3, p. 25 (1899). 

E. (Labidus) crassicorne Emery, in Wytsman Genera Insectorum, Fasc. 102, 
p. 23 (1910). 

Type loc: Villa Nova, Brazil. Types: British Museum. 

Range: southern Texas to Paraguay. 

I have seen no specimens of crassicorne coming from the United 
States but Dr. M. R. Smith assures me that workers of this species 



64 BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

have been taken at Brownsville, Texas. In all probability, even this 
southern station is north of the usual range of crassicorne. It is 
certainly not abundant in the region around Brownsville and there is 
little indication that it has established itself in that area. This is, 
however, a very difficult matter to determine in the case of an Eciton. 
Hence it seems better to include crassicorne even though it may be a 
visitor rather than an established resident within our borders. 



3. ECITON (LABIDUS) ESENBECKI (Westwood) 

Labidus esenbecki Westwood, Arc. Ent., Vol. 1, p. 75, pi. 20, fig. 4 (1842) c?. 
Eciton esenbecki Emery, Bull. Soc. Ent. Ital., Vol. 22, p. 39 (1890) cf; Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 409, pi. 26, figs. 1, 2 (1908) cf. 
E. (Labidus) esenbecki Emery in Wytsman Genera Insectorum, Fasc. 102, 

p. 23 (1910). 

Type loo: Rio Vendinha, Brazil. Types: none in this country. 
Range: southern Texas to Brazil. 

There appears to be only one record for esenbecki in the United 
States. Wheeler had a single specimen secured near Brownsville prior 
to 1908. It has been conjectured that esenbecki is the male of crassi- 
corne and the recent discovery of workers of the latter species in the 
Brownsville area certainly favors this view. But it is not likely that 
this problem will be settled by studies on our ant fauna, since both 
esenbecki and crassicorne are so rarely encountered in the United States. 
The differences which separate the male of esenbecki from that of 
coecum are given in the following key. The male of crassicorne is at 
present unknown. 

Key to the species of Labidus (males) 

1 . Anterior edge of the clypeus broadly and deeply concave; mandibles slender 

and rather suddenly bent inward in their distal third esenbecki 

Anterior edge of the clypeus straight or at most with a narrow and feeble 
concavity at the center; mandibles stouter and evenly curved throughout 

coecum 

If it can be shown that esenbecki is the male of crassicorne, the first 
name will take precedence for Westwood's description has a priority 
of thirteen years over that of Smith. 



Subgenus NEIVAMYRMEX Borgmeier 

The subgenus Neivamyrmex, which occurs widely in the New 
World, is the only doryline group well represented in the United States. 



CREIGHTON: ANTS or NOKTH AMERICA oi 

Although one species, nigrescens, occurs as far north as Illinois, Iowa 
and Nebraska, the distribution of our species is mainly southern. 
Many of them have ranges which extend into Mexico and Central 
America and one or two range into South America. The frequency of 
occurrence of the individual species and the number of species present 
in an area show an interesting divergence. The greatest concentration 
of species is found in a region comprising Texas, Oklahoma, New 
Mexico and Arizona. In this area more than a dozen species occur. 
But the incidence of the three or four species which occur in the 
southeastern states is considerably higher than that of the typically 
western species. Even the ubiquitous nigrescens, which occurs in both 
areas, seems definitely more abundant in the east. I have observed 
this same phenomenon in the field. It is usually rather difficult to find 
colonies of Neivamyrmex from the Pecos River in Texas west to the 
Pacific Coast. But in the southeastern states and along the Gulf 
Coast these insects are commonly encountered. This is a somewhat 
singular behavior for a group whose affinities are so clearly Neotropical, 
for one would expect that areas of greatest incidence would be close 
to the southern border of the United States. The explanation rests, 
I believe, on the assumption that the group is not notably xerophilous. 
This view can be supported despite western records from stations that 
are clearly in desert country. For the larger number of western records 
come from canyons in the foothills of mountains and it is only in such 
stations that the insects appear to be at all abundant in the west. 
This results in a much more sporadic distribution in Arizona, New 
Mexico and western Texas than that which marks the species in the 
southeastern states. There is a further possibility that the arid climate 
of the western states forces the species which occur there to adopt a 
more completely subterranean life. If, as seems likely, many of the 
western species forage above ground only at night, this circumstance 
would certainly tend to keep them out of the hands of collectors. 

Relatively little is known of the habits of our representatives of 
Neivamyrmex. The species are said to construct nests and it seems 
to be generally assumed that these are comparable to the nests of 
most ants. It is likely, however, that the principal basis for this view 
is the fact that most of our species of Neivamyrmex utilize chambers 
in soil under stones, etc. It is not clear that they build these chambers 
nor is it certain that they occupy them for any protracted period. In 
1901 Wheeler and Long presented an account of a nest of -nigrescens 
(schmitti) which they discovered. In this nest the chambers contained 
much brood of nigrescens and a quantity of brood which had been 
pilfered from other ant colonies. It may be noted that there is nothing 
in the above account that would clash with the view that what 



DO BULLETIN: MUSEUM OP COMPARATIVE ZOOLOGY 

Wheeler and Long discovered was a statary phase of nigrescens and 
that the 'nest' was actually a permanent bivouac made during the 
period when the brood was about to pupate. The foraging activities 
of Neivamyrmex are much less spectacular than those of the species 
of Eciton sens sir. As far as the writer has been able to observe the 
foraging workers never form a compact column but run rapidly over 
the ground strung out in a single line. While thus engaged the workers 
constantly explore the ground ahead of them with the antennae which 
are twitched with a characteristic flicking motion. In all probability 
they are following a scent trail laid down by previous workers. 
Schneirla has demonstrated the importance of such scent trails in the 
foraging activities of some of the species of Eciton. The food secured 
by Neivamyrmex appears to consist mainly of other insects. According 
to Wheeler and Long (vide supra) this is brought into the nest and 
stored for a time before being eaten. If the nest site is changed this 
stored food is moved to the new site. Nothing is known as to the 
mating reactions of these insects and the only observation of any sort 
in this connection appears to be that published by Dr. M. R. Smith 
in 1942. He reports that D. E. Read took a male and female of 
carolinense in copula. Since this pair was in the nest when secured the 
presumption is that mating takes place between brothers and sisters 
of the same colony. Dr. Smith believes that daughter colonies are 
probably formed by migration. 

Of the keys which follow those for the identification of the males 
and females have been taken directly from Dr. M. R. Smith's 1942 
monograph of Neivamyrmex. The key to the workers is also based 
largely on the separatory characters which were given in the above 
monograph but the order in which they are presented has been altered 
and certain minor changes have been introduced. It may be added 
that anyone interested in the taxonomy of Neivamyrmex should 
certainly secure a copy of Dr. Smith's monograph for it is, by a very 
wide margin, the most satisfactory treatment of our species. 

Key to the major workers of Neivamyrmex 

1. Entire upper surface of the head completely opaque, evenly covered with 
fine, contiguous punctures and with larger shallow depressions (also 

punctate) from which the erect hairs arise nigrescens 

Upper surface of the head entirely or in large part shining, the surface 
between the piligerous punctures without sculpture over much of the 
head 2 

2. Anterior peduncle of the petiole with a long, sharp, slender spine which 
is directed downward and to the rear and is attached to the base of the 
peduncle by a transparent lamella pilosum 



CEEIGHTON: ANTS OF NORTH AMERICA o7 

Anterior peduncle of the petiole without such a spine, at most with a 
short anterior tooth, angle or projection which is directed downward or 
slightly forward 3 

3. Node of the petiole in profile subtriangular, with a distinctly rounded 
crest and an anterior face which slopes gradually to the peduncle; sides 
of the epinotum abruptly compressed in its upper half. . .melanocephalum 
Node of the petiole in profile subrectangular, elongate, flat or feebly convex 
above and with the anterior face abruptly descending to the peduncle; 
sides of the epinotum feebly or not at all compressed in their upper half. . 4 

4. Petiole from above almost twice as long as broad, slender and not sub- 
quadrate .' 5 

Petiole from above as broad as long or if a little longer than broad it is 
robust and subquadrate 6 

5. Entire dorsura of the thorax densely sculptured and opaque, only the 

propleurae shining opacithorax 

Promesonotum and propleurae feebly to strongly shining . . . calif ornicum 

6. Frontal lobes high, thin, flange-like and carried part way around the front 
of the antennal socket as a transparent lamina which projects a little 

beyond the edge of the clypeus 7 

Frontal lobes low, not notably flange-like and, if carried part way round 
the front of the antennal socket, the rim is low, not transparent and does 
not project beyond the edge of the clypeus 8 

7. Occipital angles very pronounced and ear-like, often reflected outward; 
eyes distinct; pronotum often subopaque with coarse punctures, rugae and 

shagreening; length of largest worker 4.5 mm wheeleri 

Occipital angles blunt; eyes absent; pronotum smooth and shining with 
fine punctures only; length of largest worker 3 mm leonardi 

8. Head (mandibles excluded) approximately one and one third times longer 
than broad; gaster distinctly flattened; length of largest worker 2 mm. 

pauxillum 

Head (mandibles excluded) approximately one and one eighth times 
longer than broad; gaster not flattened; length of largest worker at least 
3.5 mm 9 

9. Dorsum of the thorax very smooth and shining, punctate only; antennal 
scape slightly more than two and one half times as long as it is thick at 

the tip; funicular joints 2-6 notably broader than long commutatum 

Dorsum of the thorax heavily sculptured, subopaque; antennal scape 
about three and one half times as long as it is thick at the tip; funicular 
joints 2-6 only a little wider than long carolinense 

As Dr. Smith has pointed out, there is a strong possibility that 
leonardi and pauxillum have been described from minor workers. If 
this should subsequently prove to be the case it may be necessary to 
modify the criteria used to distinguish these two species, although 
neither of them has been brought out on the basis of size only. 



DO BULLETIN: MUSEUM or COMPAKATIVE ZOOLOGY 

Key to the females of Neivamyrmex (M. R. Smith, 1942) 

1. Head from above with the posterior corners not produced or indistinctly 

produced 2 

Head from above with the posterior corners very distinctly produced, 
angulate or t'uberculate 3 

2. Thorax more heavily sculptured and opaque than head; thorax elongate, 
gradually and perceptibly widening anteroposteriorly; prothorax sub- 
margined laterally; posterior corners of the head scarcely produced 

opacithorax 

Body smooth and shining with scattered punctures; thorax proportionally 
wider and with the posterior part of the epinotum subequal in width to 
the metanotum; prothorax more convex and scarcely, if at all, marginate; 
posterior corners of the head not produced, broadly rounded . . . carolinense 

3. Head with a distinct median impression near the occiput and an impression 
on each lateral border which causes the posterior corners to appear dis- 
tinctly angulate or tuberculate; prothorax clearly margined; thorax 
elongate, gradually widening anteroposteriorly to the metanotum; head 
and thorax subopaque or opaque, owing to the dense and rather coarse 

sculpturing nigrescens 

Head with angular posterior corners but lacking the distinct lateral im- 
pressions of nigrescens', prothorax not margined; thorax, though elongate, 
of almost uniform width from posterior half of mesonotum backward; 
head thorax and remainder of body shining even though scattered and 
distinct punctures on the former two wheeleri 



Key to the males of Neivamyrmex (M. R. Smith, 1942) 

1. Epinotum with a clearly denned, median, longitudinal groove where base 
and declivity meet; dorsum of head behind ocelli smooth, shining, concave 

and with distinct, upturned occipital flange 2 

Epinotum without a median longitudinal groove where base and declivity 
meet or else with a very weakly developed one; occipital flange either 
absent or vestigial 3 

2. Superior border of mandible with an excision near base and apex and 
between these a somewhat toothlike convexity or protuberance; antennal 
scape approximately as long as the combined length of the first 4 funicular 
segments; body and wings of a general yellowish brown color with head, 

legs and seventh gastric sternum darker pilosum 

With similar characters except that the mandible is more robust and the 
toothlike convexity of the superior border is hardly discernible 

pilosum subsp. mandibulare 

3. Mandibles sickle-shaped 4 

Mandibles not sickle-shaped 9 

4. Head, viewed anteriorly, with strongly projecting posterior corners which 
are visible between the eyes and the lateral ocelli 5 



CREIGHTON: ANTS OF NORTH AMERICA ol 

Head, viewed anteriorly, without posterior corners as described above; 
either the corners are weakly visible or else not visible 6 

5. Wings deeply infumated; mandibles extremely long, slender and curved; 
posterior corners of the head remarkably well-developed; dorsal surface 

of the gaster with short, appressed hairs fuscipennis 

Wings not infumated; mandibles, though slender and curved, not ex- 
tremely long; posterior corners of the head less well-developed; dorsal 
surface of the gaster with long, non-appressed hairs melsheimeri 

6. Small, slender species, length 8-9 mm 7 

Large species, length 11-13 mm 8 

'. Lateral ocelli borne on an elevated area which is distinctly above the level 
of the rest of the head; third funicular segment almost twice as long as 

the second, the latter notably broader than long minus 

Lateral ocelli not raised much above the level of the rest of the head; 
third funicular segment less than one and a half times as long as the 
second, the latter approximately as broad as long mojave 

8. Antenna with a long, filiform funiculus; scape not noticeably wider than 
the base of the funiculus; head, from above, not remarkably broader than 

long; tarsal claws indistinctly toothed oslari 

Antennal funiculus not long and filiform, distinctly tapering from base to 
apex; scape robust, distinctly broader than the base of the funiculus; head, 
from above, remarkably broader than long; tarsal claws distinctly toothed 

arizonense 

9. Head with unusually large eyes and ocelli; ocelli placed on a protuberance 
high above the general surface of the head; body deep brown with darker 

head and thorax harrisii 

Head with small eyes and ocelli; ocelli placed on a low protuberance which 
is scarcely elevated above the general surface of the head; color variable 
but never as described above 10 

10. From above, the dorsal surface of the head rounding off anteriorly without 
forming a very perceptible ridge above the antennal sockets; dorsal surface 
of the head and thorax, although sculptured, with a distinct glabrous 

appearance opadthorax 

From above, the dorsal surface of the head forming distinct ridges above 
the antennal sockets; dorsal surface of the thorax with a subopaque or 
opaque appearance 11 

11. Mandible remarkably long and slender, at least five times as long as 

broad; funiculus slender; length 9-9.5 mm carolinense 

Mandible more robust, not so remarkably long and slender, funiculus 
robust; length 11-13 mm nigrescens 



4. ECITON (NEIVAMYRMEX) ARIZONENSE Wheeler 

E. (Acamatus) arizonense Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 414, pi. 26, fig. 5 (1908) cf . 
E. (Neivamyrmex) arizonense M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 581, pi. 5, fig. 19 (1942) d". 



.U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: Nogales, Arizona (by Smith's 1942 restriction). 

Types: M.C.Z. 

R.ange: western Texas to southern Arizona and south to Costa Rica. 



5. ECITON (NEIVAMYRMEX) CALIFOKNICUM Mayr 

E. californicum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 969 (1870) 9 . 
E. (Lahidus) californicum Mayr, Wien Ent. Zeitschr., Vol. 5, No. 14, p. 121 

(1886) 9. 
E. (Acamatus) californicum Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 184 

(1894) 9 ; Emery, Mem. Accad. Sci. Bolgna (5) Vol. 8, p. 523 (1900) 9 . 
E. (Neivamyrmex) californicum M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 560 (1942) 9 . 

Type loc: San Francisco, California. Types: none in this country. 
Range: known from California only. 

Our present knowledge is decidedly limited as to the biology of 
californicum, for the species has been taken on comparatively few 
occasions. This circumstance makes any prediction about this insect 
a rather risky matter. I would, however, venture the opinion that 
when californicum is better known it may be necessary to synonymize 
opacithorax with californicum. It may be recalled that opacithorax was 
originally described as a subspecies of californicum. Because of its 
much greater abundance, opacithorax is now far better known than is 
californicum and this fact has tended to obscure the relationship be- 
tween the two insects. As its name indicates, opacithorax was originally 
separated from californicum because of its more extensively sculptured 
and more opaque thorax. Recently Dr. Smith has stated that cali- 
fornicum is more hairy than opacithorax. As regards this last point I 
cannot agree at all with Dr. Smith for opacithorax is often very hairy 
with the curious mixture of short and very long hairs which Dr. Smith 
describes as characteristic of californicum. Nor do I believe that much 
reliance can be placed in the differences of thoracic sculpture which 
are supposed to separate the two forms. I have before me a small 
series of workers taken at Davis, California, by Mr. Arnold Mallis. 
Some of the specimens have the shining promesonotum which sup- 
posedly marks californicum but others are heavily sculptured and fully 
as dull as opacithorax. It is possible, of course, to regard the latter 
individuals as aberrant but, if it can be shown that they are regularly 
produced in the population of californicum, it will, in my opinion, be 
very difficult to defend the validity of opacithorax. No definite settle- 
ment of this problem can be made until much more material of cali- 
fornicum has found its way into collections. 



CREIGHTON: ANTS OF NOKTH AMERICA ti 

6. ECITON (NEIVAMYRMEX) CAROLINENSE Emery 

E. (Acamatus) carolinense Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 184 (1894) 9 ; 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 259 (1895) 9 ; Wheeler, Proc. Amer. 

Acad. Arts Sci. Boston, Vol. 56, p. 314, fig. 8c (1921) <?. 
E. carolinense Forel, Ann. Soc. Ent. Belg., Vol. 43, p. 443 (1899) 9 . 
E. (Neivamyrmex) carolinense M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 564, pi. 2, fig. 11, pi. 7, fig. 22 (1942) 9 9 cf . 
Type loc: Belmont, Gaston County, North Carolina. 
Types: M.C.Z., A.M.N.H. 
Range: North Carolina and Tennessee south to the Gulf of Mexico. 



7. ECITON (NEIVAMYRMEX) COMMTJTATUM Emery 

E. (Acamatus) commutatum Emery, Mem. Accad. Sci. Bologna (5), Vol. L, 
p. 522 (1900) 9 ; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 413 
(1908) 9. 

E. (Neivamyrmex) commwtatum M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 
No. 3, p. 568, pi. 1, fig. 6 (1942) 9 . 

Type loc: Grenada, B. W. I. Types: none in this country. 

Range: in the United States, Kansas south to Texas and southwest to Arizona. 

There has always been confusion in regard to commutatum. A 
number of the older records for this insect were attributed to nitens, 
a species endemic to Argentina and Uruguay. Although Emery was 
able to present structural criteria which permit the separation of 
commutatum from nitens, our present knowledge of the distribution of 
commutatum leaves much to be desired. According to Emery, com- 
mutatum ranges as far south as Bolivia and it is certainly present in 
the Antilles. But there seem to be no records from much of Mexico 
or northern South America. Dr. M. R. Smith records commutatum 
from Texas and Arizona only, but the insect occurs as far north as 
Kansas. I have before me a series of workers of commutatum taken 
by Hayes at Winfield, Kansas. 



8. ECITON (NEIVAMYRMEX) PUSCIPENNIS Wheeler 

E. (Acamatus) spoliator Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, pi. 26, 
fig. 12 (1908) c? (figure only, not description) (nee E. spoliator Forel). 

E. (Neivamyrmex) fuscipennis M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 
No. 3, p. 578, pi. 4, fig. 15 (1942) cf . 

Type loc: Texas. Types: U.S.N.M. 

Range: known from type material only. 



! BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

The authorship of fuscipennis is an involved matter. The species 
was described by Cresson in a manuscript which was never published. 
Thereafter specimens bearing Cresson's manuscript name were ex- 
amined by W. M. Wheeler. In 1908 Wheeler assigned these specimens 
to spoliator Forel. At this time Wheeler presented a translation of 
Forel's original description of spoliator and accompanied it with a 
figure which was, presumably, drawn from one of Cresson's specimens. 
No positive proof can be given that Cresson's specimens were the 
source of Wheeler's figure. Nevertheless, the inference is very strong, 
since Wheeler mentioned no other specimens. When M. R. Smith 
described fuscipennis in 1942, he failed to make it clear that Wheeler's 
authorship of that species rests entirely upon the figure which Wheeler 
attributed to spoliator. Since Dr. Smith feels sure that this figure is 
not spoliator but fuscipennis, I have followed him in treating Wheeler 
as the author of the latter species. It should be remembered, however, 
that Dr. Smith published the first description of fuscipennis. 

9. ECITON (NEIVAMYKMEX) HARBISII (Haldeman) 

Labidus harrisii Haldeman, Stansbury's Exp. Great Salt Lake, Lippincott, 

Grambo & Co., p. 367 (1852) d". 
E. (Acamatus) harrisii Emery, Mem. Accad. Sci. Bologna (5), Vol. 8, p. 515, 

fig. 18 (1900) c?; Wheeler & Long, Amer. Naturalist, Vol. 35, p. 166, 

fig. 2 d, e (1901) cT; Wheeler, Bull. Amer. Must. Nat. Hist., Vol. 24, 

p. 413, pi. 26, fig. 10 (1908) cf . 
E. (Neivamyrmex) harrisii M. R. Smith, Amer. Mid. Naturalist, Vol. 27, No. 3, 

p. 572, pi. 6, fig. 21 (1942) d". 

Type loc: Ft. Gates, Texas. Types: none known to exist. 
Range: Oklahoma and eastern Texas west to Arizona and south into Mexico. 

Dr. Smith believes that harrisii may be the male of wheeleri. 



10. ECITON (NEIVAMYRMEX) LEONARDI Wheeler 

E. (Acamatus) leonardi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 329 

(1915) 9. 
E. (Neivamyrmex) leonardi M. R. Smith, Amer. Mid. Naturalist, Vol. 27, No. 3, 

p. 570 (1942) 9 . 

Type loc: Point Loma, San Diego, California. Types: M.C.Z. 
Range: known from type material only. 



11. ECITON (NEIVAMYRMEX) MELANOCEPHALUM Emery 

E. (Acamatus) melanocephalum Emery, Zool. Jahrb. Syst., Vol. 8, p. 260 
(1895) 9. 



CKEIGHTON: ANTS OF NORTH AMERICA 16 

E. (Acamatus) melanocephalum subsp. xipe Wheeler, Jour. N. Y. Ent. Soc., 

Vol. 22, p. 41 (1914) 9 . 
E. (Neivamyrmex) melanocephalum M. R. Smith, Amer. Mid. Naturalist, 

Vol. 27, No. 3, p. 549 (1942) 9 . 
Type loc: Tepic, Mexico. Types: U.S.N.M. 
Range: mountains of southern Arizona south into Mexico. 



12. ECITON (NEIVAMYRMEX) MELSHEIMERI (Haldeman) 

Labidus melsheimeri Haldeman, Stansbury's Exp. Great Salt Lake, Lippincott, 

Grambo & Co., p. 368, pi. 9, figs. 7, 8, 9 (1852) cT. 
E. (Labidus) melshaemeri Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 442 

(1886) cf. 
E. (Acamatus) melsheimeri Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 418, pi. 26, fig. 9 (1908) cT. 
E. (Neivamyrmex) melsheimeri M. "R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 576, pi. 4, fig. 16 (1942) rf 1 . 

Type loc: Ft. Gates, Texas. Types: none known to exist. 
Range: Oklahoma and Texas south to Costa Rica and Guatemala. 



13. ECITON (NEIVAMYRMEX) MINUS (Cresson) 

Labidus minor Cresson, Trans. Amer. Ent. Soc., Vol. 4, p. 195 (1872) cf. 

E. (Labidus) minor Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 441 (1886) cf . 

E. (Acamatus) minus Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 418, 

pi. 26, fig. 6 (1908) cf. 
E. (Neivamyrmex) minus M. R. Smith, Amer. Mid. Naturalist, Vol. 27, No. 3, 

p. 574, pi. 4, fig. 17 (1942) d 1 . 

Type loc: Bosque County, Texas. Types: A.N.S.P.; U.S.N.M. 
Range: Oklahoma and Kansas southwestward through Texas, New Mexico 

and Arizona. The insect also occurs in Mexico. 



14. ECITON (NEIVAMYRMEX) MOJAVE M. R. Smith 

E. (Neivamyrmex) mojave M. R. Smith, Lloydia, Vol. 6, p. 196 (1943) <?. 
Type loc: Mojave Desert, California. Types: U.S.N.M. 
Range: known only from type material. 



15. ECITON (NEIVAMYRMEX) NIGRESCENS (Cresson) 

Labidus nigrescens Cresson, Trans. Amer. Ent. Soc., Vol. 4, p. 194 (1872) cf. 
E. (Acamatus) nigrescens Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 417, pi. 26, figs. 7, 9 (1908) d 1 ; M. R. Smith, Proc. Ent. Soc. Wash., 

Vol. 40, p. 157 (1938) V cT . 



/4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

E. (Neivamyrmex) nigrescens, M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 
No. 3, p. 550, pi. 1, fig. 4, pi. 2, fig. 10, pi. 7, fig. 23 (1942) 9 rf 1 9 ; M. R. 
Smith, Ibid., Vol. 37, No. 3, p. 526, pi. 1, fig. 2 (1947) V . 

E. (Acamatus) schmitti Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 183 (1894) 9 ; 
Emery, Zool. Jahrb. Syst., Vol. 8, p. 258 (1895) 9 ; Wheeler & Long, Amer. 
Naturalist, Vol. 35, p. 161, fig. 1 (1901) cT; Wheeler, Bull. Amer. Mus. 
Nat. Hist., Vol. 24, p. 410, pi. 26, fig. 13 (1908) cf; Emery in Wytsman, 
Genera Insectorum, Fasc. 102, pi. 1, figs. 4, b, c, d (1910) 9 9 d"; M. R. 
Smith, Ann. Ent. Soc. Amer., Vol. 20, p. 401 (1927). 

Eciton sumichrasti Mayr (part) Verh. Zool-bot. Ges. Wien, Vol. 36, p. 440 
(1886); Wheeler, Amer. Naturalist, Vol. 34, p. 464, figs. 1, 2, 3 (1900) 9 9 
(not Norton). 

Typeloc: male Bosque County, Texas. Types: male A.N.S.P.; 
worker Doniphan, Missouri; worker M.C.Z.; 

female unknown . 

Range: coast to coast in the southern United States. In the east the northern 
limit of the range appears to lie close to Lat. 38 but in the middle west 
it extends a little north of Lat. 40. In the far west it drops to about 
Lat. 35. The insect appears to be rare in California although it is moder- 
ately abundant in parts of southern Arizona. 

In many respects it is unfortunate that it was necessary to synony- 
mize schmitti with nigrescens, for the former name has been so long 
used for the worker of this insect that a certain amount of confusion 
is to be expected. The evidence which Dr. Smith presented in 1938, 
however, clearly shows that Cresson's name must take priority. The 
range of nigrescens is by far the most extensive of any species of 
Neivamyrmex which occurs in the United States. In the middle west 
it ranges as far north as Nebraska and Iowa. Oddly enough there 
appear to be no Mexican records although the insect must certainly 
occur there. 



16. ECITON (NEIVAMYRMEX) OPACITHORAX Emery 

E. californicum subsp. opacithorax Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 184 
(1894) 9 ; Emery, Zool. Jahrb. Syst., Vol. 8, p. 259 (1895) 9 . 

E. (Acamatus) opacithorax Emery, Mem. Accad. Sci. Bologna, Vol. 8, p. 524 
(1900); Wheeler & Long, Amer. Naturalist, Vol. 35, p. 163, figs. 2c, 3 
(1901) 9 <f; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 411, pi. 26, 
fig. 4 (1908) <?. 

E. (Neivamyrmex) opacithorax M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 
No. 3, p. 555, pi. 2, fig. 9, pi. 6, fig. 20 (1942) 9 9 c?. 

E. (Acamatus) carolinense Wheeler, Proc. Amer. Acad. Arts Sci. Boston, Vol. 
56, p. 314, fig. 8 a, b (1921) 9 (not Emery). 



CREIGHTON: ANTS OF NORTH AMERICA 7o 

Typeloc: worker Doniphan, Missouri. 

female Belmont, North Carolina; 
male Austin, Texas; 
Types: worker U.S.N.M., M.C.Z.; 
female M.C.Z.?; 
male M.C.Z. 

Range: North Carolina and Tennessee south to the Gulf of Mexico and 
westward to Texas and New Mexico. The worker types appear to have 
been taken at the northern limit of the range. Doniphan is a few miles 
north of the Missouri-Arkansas border. 



17. ECITON (NEIVAMYBMEX) OSLARI Wheeler 

E. (Acamatus) oslari Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 415, 

pi. 26, fig. 8 (1908) d 1 . 
E. (Neivamyrmex) oslari M. R. Smith, Amer. Mid. Naturalist, Vol. 27, No. 3, 

p. 579, pi. 5, fig. 18 (1942) <?. 
Type loc: Nogalee, Arizona. Type: A.M.N.H. 
Range: known only from southern Arizona. Most of the records come from 

mountainous areas. 



18. ECITON (NEIVAMYRMEX) PAUXILLUM Wheeler 

E. (Acamatus) pauxillum Wheeler, Psyche, Vol. 10, p. 93, fig. 1 (1903) 9 . 
E. (Neivamyrmex) pauxillum M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 569, pi. 1, fig. 8 (1942) 9 . 
Typeloc: Austin, Texas. Types: A.M.N.H.; M.C.Z. 
Range: central and western Texas. 



19. ECITON (NEIVAMYRMEX) PILOSUM F. Smith 

E. pilosa F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 151 (1858) 9 . 

E. pilosum Mayr, Novara Reise Formicid., p. 77 (1865); Mayr, Wien Ent. 

Zeit., Vol. 5, p. 120 (1886). 
E. (Acamatus) pilosum Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 183 (1894) 9 ; 

Emery, Mem. Accad. Sci. Bologna (5), Vol. 8, p. 524 (1900) 9 . 
E. (Neivamyrmex) pilosum M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 544, pi. 1, fig. 7, pi. 3, fig. 13 (1942) 9 d" . 

Labidus mexicanum F. Smith, Cat. Hym. Brit. Mus., Vol. 7, p. 7 (1859) cT. 
E. (Acamatus) mexicanum Emery, Mem. Accad. Sci. Bologna (5), Vol. 8, 

p. 515, fig. 19 (1900) c?; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 414, pi. 26, fig. 11 (1908) c7; Wheeler, Proc. Amer. Acad. Arts Sci. 

Boston, Vol. 56, No. 8, p. 313, fig. 7 (1921) d 1 ; M. R. Smith, Jour. N. Y. 

Ent. Soc., Vol. 39, p. 295 (1931) d". 
Eciton davicornis Norton, Trans. Amer. Ent. Soc., Vol. 2, p. 46 (1868) 9 . 



<o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Eciton subsulcatum Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 440 (1886) rf 1 . 
Type loc: worker Villa Nova, Brazil. Types: British Museum. 

male Orizaba, Mexico. 

Range: Mississippi and Arkansas westward through Oklahoma and Texas and 
southward to Brazil. 



20. ECITON (NEIVAMYEMEX) PILOSUM MANDIBULARE M. R. Smith 

E. (Neivamyrmex) pilosum subsp. mandibulare M. R. Smith, Amer. Mid. 

Naturalist, Vol. 27, No. 3, p. 548, pi. 3, fig. 14 (1942) d". 
Type loc: Thirty miles east of Quijotoa, Pima Co., Arizona. 
Types: U.S.N.M., Coll. Cornell Univ. 
Range: known from southern Arizona only. 

Dr. Smith has shown that the specimens of pilosum (mexicanum) 
which Wheeler recorded from Nogales belong to mandibulare and he 
is of the opinion that specimens from Las Cruces, New Mexico, also 
belong to this subspecies. The range of the typical pilosum would, 
therefore, appear to terminate in western Texas and that of the sub- 
species mandibulare would begin in that area and run westward 
through southern New Mexico and Arizona. 



21. ECITON (NEIVAMYRMEX) WHEELEEI Emery 

E. (Acamatus) wheeleri Emery, Bull. Soc. Ent. Ital., Vol. 33, p. 55 (1901); 

Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 412 (1908) 9 . 
E. (Neivamyrmex) wheeleri M. R. Smith, Amer. Mid. Naturalist, Vol. 27, 

No. 3, p. 561, pi. 1, fig. 5 (1942) 9 9 . 
E. (Acamatus) wheeleri subsp. dubia Creighton, Psyche, Vol. 39, p. 73, pi. 3, 

figs. 1, 2, 3 (1932) 9 9 . 
Type loc: worker Hays County, Texas. 

female Ft. Worth, Texas; 
Types: worker M.C.Z.; 

female Coll. W. S. Creighton. 
Range: central Texas south into Mexico. 

I agree with Dr. Smith that the subspecies which I described as 
dubia is a synonym of wheeleri. At the time when dubia was described 
I had no material of wheeleri for comparison and the characters em- 
ployed for the recognition of dubia were those reported by Wheeler, 
to whom specimens had been sent for comparison with the types of 
wheeleri. I have since been able to examine the types of wheeleri and 
have seen considerable additional material belonging to this species. 
Dr. Smith is quite correct in stating that the characters which sup- 
posedly mark dubia are inconstant and without taxonomic significance. 



CREIGHTON: ANTS OF NORTH AMERICA 

Subfamily PSEUDOMYRMINAE 

Genus PSEUDOMYRMA Latreille 
(Plate 13, figures 1-4) 

There has been such a notable lack of uniformity regarding the 
authorship of the genus Pseudomyrma that some attempt must be 
made to clarify the existing confusion. At different times Pseudo- 
myrma has been attributed to Latreille, Lund, Guerin and Frederick 
Smith. It is difficult to understand why this situation has arisen, for 
the point involved is not complicated. In 1804 Fabricius described 
three new species of Neotropical ants (gracilis, tennis and filiform/is) 
and these he assigned to the old, heterogeneric, Linnaean genus 
Formica. Latreille later recognized these species as representatives of 
a separate genus, which he proposed to call Pseudomyrma. His 
suggestion was not published under his own name but carried in a 
paper by Lund, that appeared in 1831. There seems to be no question 
that this represents the earliest date for the use of the generic name 
Pseudomyrma. Since Guerin did not employ the name until 1845 and 
F. Smith even later (1855), there is no possible justification for con- 
sidering either of these men as the author of the genus Pseudomyrma. 
The question involved turns upon whether Lund intended to attribute 
the authorship of Pseudomyrma to Latreille. Carlo Emery, the only 
myrmecologist who seems to have given much thought to this matter, 
is of the opinion that this was the case, and that Latreille must be 
considered the author of Pseudomyrma. I see nothing to be gained 
by contesting this point and trust that other students of ants may see 
the matter in the same light. 

The subfamily Pseudomyrminae is a comparatively small group 
consisting of four genera. Three of these are confined to the Old World 
tropics. The fourth genus, Pseudomyrma, is found only in the New 
World and the great majority of the species which compose it are 
limited to the tropics. There are, however, a few species which range 
into subtropical areas. Of these, only four have a distribution which 
brings them within the borders of the United States. Because of this 
our species can be readily handled, despite the fact that the taxonomy 
of Pseudomyrma is hopelessly involved. Throughout the genus there 
is an unusually close structural similarity between species. Moreover, 
many species are highly variable in minor features and these variations 
have often been named. It is often impossible to secure a clear cut 
distinction between species and it is not surprising that most myrme- 
cologists have made no attempt at monographic studies on Pseudo- 
myrma. The one effort in this direction is the survey published by 
Enzmann in 1944. Although Enzmann's studies were based in large 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



part on the Wheeler Collection in the Museum of Comparative 
Zoology, he failed to avail himself of this excellent opportunity for 
sound revisionary work. Instead his incredible disregard for the most 
basic rules of nomenclature has produced a paper that is little more 
than a taxonomic curiosity. No reliance can be placed in Enzmann's 
descriptions, keys or figures and about the only result of his study 
has been to make confusion much worse confounded. 

The habits of Pseudomyrma appear to be remarkably uniform. 
They are usually spoken of as arboreal insects but it is more accurate 
to say that they prefer to nest in preformed plant cavities. If the 
cavity is suitable the size of the plant seems to be a matter of little 
concern, hence they will nest with equal freedom in the hollow twigs 
of trees, the stalks of herbaceous plants and even in the stems of some 
of the larger grasses. Many of the species are, nevertheless, restricted 
to one species of plant or even to one part of a plant. Among these 
are the celebrated Acacia ants, which nest in the swollen bases of the 
large spines that give the bull-horn Acacia its popular name. Most 
species of Pseudomyrma are active and agile insects. Some of them 
are surprisingly aggressive, particularly in resisting any disturbance 
to the nest. The feeding habits of the adult Pseudomyrma show little 
evidence of specialization. So far as is known, all the species are 
omnivorous, feeding upon honeydew, the softer tissues of plants and 
the tissues of other insects. Their method of feeding the larvae, on 
the other hand, is a peculiar and specialized process found in all the 
pseudomyrmine genera but not known elsewhere in the Formicidae. 
We owe our knowledge of the feeding habits of the larval stages of 
Pseudomyrma almost entirely to the investigations of Wheeler and 
Bailey who, in 1920, published an exhaustive account of this matter. 
The brief summary presented in the following paragraph is only a 
small part of the information contained in their admirable study. 

The head of the pseudomyrmine larva is quadrate in shape and 
larger than that of other ant larvae. Beneath it lies a cluster of 
papillae (the exudatoria) which arise from the thoracic and the first 
abdominal segments. Between these papillae the first abdominal 
segment is expanded into a sort of a shelf or pocket (the trophothylax) 
that underlies the mouth of the larva. Food is placed in this pocket 
by the workers. This food is of a very unusual sort. It consists of bits 
of tissue which have collected in the infrabuccal pocket of the worker 
and from which most of the juices have been sucked by the worker 
before it is deposited on the trophothylax of the larva. The deposited 
pellet is, therefore, rather firm and dry, and not available for im- 
mediate ingestion by the larva. But the larva proceeds to rectify this 
matter by grinding the pellet between two opposable plates (the 



CKEIGHTON: ANTS OF NOKTH AMEBICA , 

trophorinium) which are covered with very fine striae. After the pellet 
has been finely comminuted the fragments are swallowed. It is pre- 
sumed that this process of comminution not only makes it possible 
for the larva to swallow the pellet but also releases particles of food 
which had escaped digestion in the infrabuccal pocket of the worker. 
It may be added that in all other ants except the Pseudomyrminae 
the contents of the infrabuccal pocket are regularly discarded. 

Key to the species of Pseudomyrma 

1. Erect hairs numerous on all parts of the body and the appendages; length 
8 mm. or more; head, thorax and petiole maculate, black and reddish 

yellow, gaster black gracilis subsp. mexicana 

Erect hairs sparse or absent on body and appendages; length 5 mm. or 
less; concolorous or nearly so 2 

2. Head, thorax and gaster covered with fine, dense, appressed, greyish 
pubescence; upper surface of the head and thorax strongly shagreened and 

duE elongata 

The appressed pubescence very sparse or lacking altogether over much of 
the body; upper surface of the head and thorax feebly shagreened or with 
small scattered punctures, the surface moderately to strongly shining 

3. Mesoepinotal suture strongly impressed; the sides of the postpetiole which 
slope inward to the anterior peduncle slightly concave when viewed from 
above; head and thorax yellowish brown, the entire gaster blackish brown 

brunnea 

Mesoepinotal suture feebly impressed; the sides of the postpetiole which 
slope inward to the anterior peduncle straight or slightly convex when seen 
from above; color clear yellow, the gaster often with two brownish spots 
at the base pallida 

1. PSEUDOMYRMA BRUNNEA F. Smith 

Ps. brunnea F. Smith, Trans. Ent. Soc. Lond., p. 63 (1877) 9 ; Emery, Zool. 

Jahrb. Syst., Vol. 8, p. 269 (1895) 9 9 ; Forel, Biol. Centr. Amer. Hym., 

Vol. 3, p. 97 (1899) 9 ; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 420 (1908) 9 9 . 

Typeloc: Mexico. Types: none in this country. 
Range: South Carolina south into Florida and westward through the southern 

portion of the Gulf Coastal Plain into Mexico. 



2. PSEUDOMYRMA ELONGATA Mayr 

Ps. elongata Mayr, Sitz. ber. Akad. Wien, Vol. 61, p. 413 (1870) 9 ; Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 85 (1905) 9 9 d". 
Type loc: New Grenada, B. W. I. Types: none in this country. 



oil BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Range: southern Florida. It is interesting to note that the typical elongata 
ranges southward through the Bahamas and the Lesser Antilles to 
Colombia. It has produced distinct geographical races in Cuba, Haiti 
and Central America but it is not at present known from Mexico although 
it may occur in the southern portion of that country. These facts seem 
to indicate rather clearly that elongata entered the United States through 
the Antilles and not by way of Mexico. 

3. PSEUDOMYRMA GRACILIS MEXICANA Roger 

Ps. mexicana Roger, Berl. Ent, Zeitschr., Vol. 7, p. 178 (1863) 9 . 

Ps. gracilis var. mexicana Mayr, Sitz. Verh. Akad. Wis. Wien, Vol. 61, p. 409 

(1870); Emery, Bull. Soc. Ent. Ital., Vol. 22; p. 60, pi. 5, fig. 16 (1890) 9 . 
Ps. gracilis subsp. mexicana Forel, Mitt. Naturh. Mus. Hamburg, Vol. 24, 

p. 7 (1907); Enzmann, Psyche, Vol. 51, Nos. 3, 4, p. 65, pi. IV, figs. 29, 33 

(1944) 9. 

Typeloc: Mexico. Types: none in this country. 
Range: the Brownsville region of Texas and south into Mexico. 



4. PSEUDOMYRMA PALLIDA F. Smith 

Ps. pallida F. Smith, Trans. Ent. Soc. Lond. (2), Vol. 3, p. 160 (1855) 9 ; 

Forel, Biol. Centr. Amer. Hymenop. Ill, p. 92 (1899) 9 ; Wheeler, Bull. 

Amer. Mus. Nat. Hist., Vol. 24, p. 419 (1908) 9 . 

Ps.flavidulavai. pallida, Enzmann, Psyche, Vol. 51, Nos. 3, 4, p. 66 (1944) 9 . 
Ps.flavidula M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 544, pi. 5, 

fig. 17 (1947) 9 . 

Type loc: east Florida. Types: none in this country. 
Range: South Carolina south to Florida and westward through the southern 

portion of the Gulf Coastal Plain into Mexico. There are also scattered 

records from southern Arizona and southern California. The insect occurs 

widely throughout the Antilles, Mexico, Central America and as far south 

as the Amazon Basin in South America. 

For many years myrmecologists have displayed a surprising agility 
in skirting the problem of what to do with pallida and flamdula. It 
seems time that someone grasped the nettle and attempted a clarifi- 
cation of the problem, particularly as a recent blunder by Enzmann 
has added new confusion. In his study on Pseudomyrma, Enzmann 
treated pallida as a variety of flamdula. Since pallida was described 
in 1855 and flamdula in 1858 the first name clearly has priority and 
Enzmann's treatment is a violation of the rules of nomenclature. But 
this is by no means the worst that can be said of Enzmann's error. 
It clearly calls for rectification and the correction which is almost 
certain to be proposed is the transposition of the two names with 



CREIGHTON: ANTS OF NORTH AMERICA 



flavidula made a variety of pallida. Thus Enzmann has set the stage 
for the synonymization of flavidula, a step which has been sedulously 
avoided by myrmecologists for almost a century. If flavidula is to be 
regarded as cospecific with pallida it should be for a better reason than 
the need for correcting Enzmann's mistake. The relationship of 
flavidula to pallida is a highly complicated matter and there is reason 
to believe that at present it is impossible to clear away all the diffi- 
culties which are involved. But it is certain that much can be done 
toward bettering our knowledge of the problem insofar as it applies 
to the specimens which occur in the United States. As will be shown 
in a subsequent paragraph, these specimens are of special significance. 
It is best to begin this discussion with the event which is responsible 
for the problem the description of flavidula by Frederick Smith 
in 1858. 

Smith's flavidula was saved from the limbo which holds many of 
his unrecognizable species by the fact that its original description 
carried a reference to a very minor detail of color. The gaster was 
marked at the base by two brownish spots, instead of being entirely 
yellow as in the case of pallida. Myrmecologists are not, as a rule, 
inclined to place much trust in color as a character for specific de- 
termination. Yet despite two subsequent descriptions of the worker 
of flavidula and other efforts which have been made to give it morpho- 
logical distinction, it is a fact that gastric coloration is still the principal 
criterion for the recognition of flavidula. Since Smith's description is 
otherwise worthless, there is a sound reason for this unusual situation. 
If one is not prepared to accept flavidula as a version of pallida with 
a spotted gaster then there is no way of telling what it is. 

In their preoccupation with these gastric markings, most myrme- 
cologists appear to have neglected certain geographical data which 
were also included in Smith's descriptions. The type of pallida came 
from eastern Florida, that of flavidula from Santarem, Brazil. This 
circumstance enables us to be certain of what pallida is without 
reference to a type and despite Smith's inadequate description. For 
there are only three species of Pseudomyrma in Florida and only one 
of them is yellow. Moreover the population of this yellow Pseudo- 
myrma shows an astonishing uniformity of structure. Indeed the only 
variable feature about it is the gastric coloration which may be either 
clear or spotted. It is certain, therefore, that the type of pallida must 
have come from this population. No such certitude is possible in the 
case of flavidula. There are a number of yellow species of Pseudo- 
myrma in northern Brazil and several of them show gastric markings. 
Smith's description might apply to any one of these species. It is easy 
to appreciate why little mention has been made of this latter fact. No 



oZ BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

one has wished to admit that flamdula is an unrecognizable species. 
But to repeat what was said at the end of the last paragraph, if one 
is not prepared to accept flamdula as a version of pallida with a spotted 
gaster then there is no way of telling what it is. 

I wish to stress the last point strongly, for it is clear that this is 
exactly what most myrmecologists have done. They have given the 
name flamdula to specimens of pallida which have gasters with brown 
spots. That such specimens are not specifically distinct is true, indeed 
they do not seem to deserve even varietal status. But it is one thing 
to show that these specimens are specifically identical with pallida and 
quite another to prove them the same as the insect to which Smith 
gave the name flamdula. The remedy to the pallida-flamdula problem 
involves not the synonymization of flamdula, but the realization of 
the fact that the gaster of pallida is not always a clear yellow. This 
view will probably be difficult to establish since it runs counter to 
customary practice. Despite the fact that there are always "off 
colored" individuals in a nest series of any length, the significance of 
these is usually disregarded. If any specimens with spots are present 
the colony is plainly "flamdula," hence most of the records of pallida 
are based upon strays and fragments of colonies. It follows that there 
will always be a great many more records for "flamdula" than for 
pallida and this is clearly shown in Wheeler's 1932 publication on 
Florida ants. The records for "flamdula" are three times as numerous 
as those for pallida and Wheeler explained this on the assumption that 
the latter insect was "less abundant". What he actually had was a 
demonstration of the fact that it is virtually impossible to find a nest 
series of pallida in which there are not some individuals with spotted 
gasters. 

The broader aspects of the pallida-flamdula problem lie outside the 
scope of this book. For its final solution will involve the reexamination 
of Smith's type of flamdula, assuming that this still exists, and a much 
better knowledge of the South American species of Pseudomyrma than 
we have at present. But this is a difficulty which need trouble only 
those who have to deal with the ants of that region. As far as the 
student of North American ants is concerned the pallida-flamdula 
problem ceases to exist the moment that he recognizes the inherently 
variable color pattern in the gaster of pallida. 



Subfamily MYRMICJNAE 

It is difficult to speak in general terms about the Subfamily Myrmi- 
cinae, for no other group of ants shows so much variation in morphology 
and habits. Some of the genera have retained a rather primitive 



CREIGHTON: ANTS OF NORTH AMERICA } 

structure (Myrmica, Manica); others are among our most highly 
evolved ants (Strumigenys, Cryptocerus, etc.). The majority of the 
genera fall between these extremes in the amount of structural differ- 
entiation which they show. 

These ants exhibit so many different sorts of habits that it is 
possible to give only the more general patterns here. An entire group 
of genera in the tribe Attini are fungus growers and their activities 
in cultivating their fungus gardens are among the most remarkable 
to be found in ants. Many genera are highly graminicolous (Pogono- 
myrmex, Veromessor, Pheidole etc.) and those species in which this 
trait is best developed are often found in arid or desert areas. There 
are at least two genera whose representatives are largely arboreal 
(Xenomyrmex, Cryptocerus). There is one genus of slavemakers 
(Harpagoxenus) and three of workerless parasites (Sympheidole, 
Epoecus and Anergates). The genus Leptothorax contains a number 
of species which are inquilinesin the nests of other ants andSolenopsis 
has a high proportion of species which behave as thief ants. It is 
interesting to note that one of the few genera which appears to be 
entirely carnivorous is the highly developed Strumigenys. These 
remarkable ants, so far as is known, live largely on Collembola, which 
they capture by a combination of stealth and the use of a peculiar 
mandibular mechanism. Hence it is probable that this carnivorous 
diet represents a secondary specialization rather than a retention of 
the primitive feeding habits of the ponerines. 



Key to the Genera of the Subfamily Myrmidnae 

1. Workers absent 2 

Workers present _ 

2. Gaster of the female with a broad impression at the base of the gaster or 

with a deep longitudinal furrow extending its full length 3 

Gaster of the female without basal impression or longitudinal furrow .... 

Sympheidole 

3. Gaster of the female with a broad flat impression on the dorsum of the 

first segment Epoecus 

Gaster of the female with a deep longitudinal furrow extending its full 
length Anergates 

4. Antennae with six segments Strumigenys 

Antennae with more than six segments 5 

5. Body much flattened, the frontal carinae very large and expanded laterally 
so that they form an overhanging rim at the edge of the head, beneath 
which is a deep scrobe for the reception of the antennae; head of the major 
appearing like a shallow, oval saucer when viewed from above 

Cryptocerus 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Body not flattened, antennal carinae not as described above, the head of 
the major, when that caste is present, not saucer-like when viewed from 
above 6 

6. Postpetiole attached to the dorsal surface of the first gastric segment, the 
gaster flattened dorsally but much more convex ventrally, acutely pointed 

behind Crematogaster 

Postpetiole attached to the anterior end of the first gastric segment, the 
gaster about equally convex above and below and not notably pointed 
behind 7 

7. Antennae with ten segments, the last two forming a very distinct club . . 

Solenopsis 

Antennae with more than ten segments, the club, if present, only rarely 
of two segments 8 

8. Antennae with eleven segments 9 

Antennae with twelve segments 19 

9. Dorsum of the pronotum, mesonotum and epinotum with spines, teeth, 
rounded bosses or prominent ridges present; antennal fossa always 
bounded by a delicate carina which runs diagonally inward from the 

insertion of the mandible past the inner border of the eye 10 

Dorsum of the pronotum and mesonotum without spines, projecting 
bosses or ridges; spines and teeth, when present, confined to the epinotum; 
antennal fossa only rarely bordered by a diagonal carina and when this 
is present the size of the worker does not exceed 2 mm 14 

10. Frontal carinae projecting forward above the clypeus, largely or entirely 
concealing its lateral portions when the head is viewed from above; 

thoracic spines, when present, short and dentiform 11 

Frontal carinae shorter, not projecting above the clypeus or at most 
projecting over its posterior half, the full width of the clypeus visible from 
above; thoracic spines long and prominent . .' 12 

11. Pro-, meso- and epinotum each with a pair of short teeth or denticles; 
body hairs at least in part erect, those of the gaster arising from small 

but distinct tubercles Mycetosoritis 

Pro-, meso- and epinotum with bosses or carinae but not armed with 
denticles; body hairs scale-like, appressed; gaster not tuberculate 

Cyphomyrmex 

12. Thoracic dorsum armed with three pairs of spines; large highly poly- 
morphic species, the length of the worker varying from 2-12 mm Atta 

Thoracic dorsum armed with more than three pairs of spines; less poly- 
morphic or monomorphic species of smaller size, length 6 mm. or less. . 13 

13. Entire insect, including the antennal scapes and legs, covered with numer- 
ous small tubercles; frontal carinae extending almost to the posterior 

corners of the head; occipital emargination shallow Trachymyrmex 

Tubercles confined largely to the gaster, postpetiole and the tops of the 
occipital lobes; frontal carinae indistinct behind and not extending to the 
occipital corners; occiput deeply emarginate in the largest workers 

Acromyrmex 

14. Epinotum unarmed; petiole subcylindrical, without a node above 

Xenomyrmex 



CEEIGHTON: ANTS OF NORTH AMERICA 85 

Epinotum armed with spines or short teeth; node of the petiole well 
developed 15 

15. Antennal club very distinct and consisting of two segments which are 
notably broader and longer than the seven small segments that precede 

them Erebomyrma 

Antennal club, if present, consisting of more than two segments, usually 
not separated abruptly from the remainder of the funiculus 16 

16. Frontal carinae extending rearward at least two-thirds of the distance to 
the posterior corners of the head and each bordering a shallow scrobe for 
the reception of the antennal scape, the latter often much flattened. . . 17 
Frontal carinae short, no antennal scrobes present, the antennal scape 
not flattened Leptothorax 

17. Postpetiole strongly transverse; humeri rounded; length 3.2 mm. or 

more '. lg 

Postpetiole about as broad as long; humeri markedly angular; length 
1.5-2 mm Wasmannia 

18. Antennal scrobe narrow, usually obliterated by the heavy sculpture except 
immediately under the overhanging edge of the frontal carina; head, 

thorax and petiolar nodes strongly reticulo-rugose Xiphomyrmex 

Antennal scrobe broad, its width extending almost to the inner border of 
the eye; sculpture everywhere delicate Harpagoxenus 

19. Middle and hind tibial spurs very finely pectinate, the teeth distinct and 
regular but usually too small to show unless a magnification of 100 

diameters or more is used ' 20 

Middle and hind tibial spurs simple or absent, very rarely with a few 
barbules but never pectinate 22 

20. Thoracic dorsum with the sutures obsolescent or absent; thorax not im- 
pressed between the mesonotum and epinotum; psammophore usually 

present Pogonomyrmex 

At least the mesoepinotal suture present and distinct on the thoracic 
dorsum; thorax impressed at the mesoepinotal suture; psammophore 
absent 21 

21. Epinotum armed with spines or teeth; promesonotal suture absent on the 
thoracic dorsum; mesoepinotal suture moderately impressed. . . .Myrmica 
Epinotum not armed with spines or teeth, usually evenly rounded but 
rarely with blunt protuberances present; promesonotal suture visible on 
the thoracic dorsum but often faint; mesoepinotal suture strongly im- 
pressed Manica 

22. Petiole subcylindrieal, without a distinct node above Myrmecina 

Petiole with a distinct node, the anterior peduncle distinct, even when 
short 23 

23. The lateral portions of the clypeus raised behind into a narrow ridge or 
carina which forms an abrupt, semicircular boundary at the front of the 

antennal fossa 24 

The lateral portions of the clypeus not raised in a semicircular ridge be- 
hind; the antennal fossae opening onto the clypeus without a boundary or 
occasionally the entire lateral portion of the clypeus tilted to the rear so 
that it forms a sloping boundary to the antennal fossa 2K 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



24. Many of the numerous, erect body hairs branched or trifid . . Triglyphothrix 
Erect body hairs simple Tetramorium 

25. Epinotum unarmed, the basal face at the same level as the dorsum of the 

mesonotum Monomorium 

Epinotum usually armed with spines or teeth but, if unarmed, the basal 
face is distinctly below the level of the dorsum of the mesonotum. . . .2" 

26. Worker caste dimorphic (rarely polymorphic) with the head of the major 

disproportionally large Pheidole 1 

Worker caste monomorphic, or if polymorphic, the head of the major is 
not disproportionally large 27 

27. Thoracic dorsum with the mesoepinotal suture absent or very faintly 

indicated 28 

Thoracic dorsum with the mesoepinotal suture well-marked 30 

28. Large species, 10^12 mm. in length with the antennal scapes projecting 

well beyond the occipital border Novomessor 

Small species not over 4 mm. in length and often less; the antennae 
usually not surpassing the occipital border and never projecting much 
beyond it , 29 

29. Thoracic dorsum flat or feebly convex in profile; anterior peduncle of the 
petiole short, thick and not sharply set off from the node; epinotal spines 

short or at most of moderate length Leptothorax 

Thoracic dorsum distinctly convex in profile; anterior peduncle of the 
petiole long, usually thin and always sharply set off from the node; 
epinotal spines long Macromischa 

30. Epinotum depressed well below the level of the pronotum, in profile the 
mesonotum forming a sloping declivity between them; antennal club 

indistinct, of 4-5 segments 31 

Thorax seen in profile with the epinotum as high as the promesonotum, 
the thoracic dorsum usually forming an unbroken plane, more rarely with 
the epinotum separated from the mesonotum by a deep impression; 
antennal club of three segments Leptothorax 2 

31. Postpetiole only slightly constricted behind, the node low and not sharply 
set off from the thick posterior peduncle; head quadrate, not notably 
narrower behind the eyes than in front of them; psammophore often 

present Veromessor 

Postpetiole more strongly constricted behind, the node distinct and 
sharply set off from the posterior peduncle; head longer than broad and 
often much narrower behind the eyes than in front of them; psammophore 
never present Aphaenogaster 

1 Since the discovery of the minor worker of Epipheidole by Dr. M. R. Smith there is no 
satisfactory way in which this genus can be separated from Pheidole. It is not a workerless 
parasite, as was formerly supposed, and the breakdown of this characteristic has destroyed the 
main distinction on which the recognition of Epipheidole was based. Means for separating 
Epipheidole inguilina from its host, Ph. pilifera coloradensis have been given elsewhere.' 

a There seems to be no satisfactory structural distinction by which the worker of Symmyrmica 
can be separated from Leptothorax. The presence of an impressed mesoepinotal suture will 
not separate this insect from species in the subgenus Dichothorax. Since the main generic 
distinction of Symmyrmica appears to be its ergatoid male, this feature must be used to dis- 
tinguish it from Leptothorax. 



CREIGHTON: ANTS OF NORTH AMERICA i 

Genus MYRMICA Latreille 
(Plate 14, figures 1-4) 

At the present time the taxonomy of the genus Myrmica is in a 
condition of unparalleled complexity. Repeated revisions of the 
group have intensified rather than diminished this situation. Since 
certain proposals followed in this volume differ from the treatment 
previously accorded to some of our representatives, it is necessary 
to present an account of earlier taxonomic developments within the 
genus Myrmica. 

For many years after Latreille established the genus Myrmica it 
contained only two species, the Linnaean rubra and Latreille's species 
rubida (now in the genus Manica). In 1846 Nylander added five new 
species, laemnodis, lobicornis, ruginodis, scabrinodis and sulcinodis. 
The genus retained essentially this character until 1874, at which 
time Forel published his Fourmis de la Suisse. In this work Forel 
treated all of Nylander's species as races of rubra. This association 
was primarily based on the structural similarities of the worker caste. 
While Forel's view was too extreme it served to emphasize the lack 
of good delimiting characters in the case of the worker. Before other 
students could restore the various forms to specific status they were 
compelled to present better reasons than the fine distinctions which 
marked the worker. These reasons, when they appeared, involved 
the structure of the male. After a few years lobicornis was restored 
to specific rank because the male possesses an antennal scape which 
is bent at the base. A difference in the number of joints which form 
the funicular club permitted the restoration of scabrinodis to specific 
status. 

The utility of the male in specific delimitation soon led to its use 
as a means for subspecific recognition. As will be shown, the results 
of this practice have not always been satisfactory. The particular 
instance which concerns the student of North American ants is the 
sabuleti-schenki tangle. This forms one of the rare lapses in Emery's 
excellent monograph of our ant fauna. The form sabuleti had been 
described by Meinert as a separate species in 1860. Thereafter it 
had been generally neglected until Emery suddenly referred to it in 
the 1895 portion of his treatise on North American ants. Meinert's 
types of sabuleti had been taken in Norre-Vosberg, Denmark, a fact 
which did not deter Emery from stating that sabuleti is the commonest 
form of Myrmica in America. Emery seemed much surer of these 
American specimens than of the "almost identical" European form 
which he assigned to Meinert's species. Emery frankly admitted that 



BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 



there was no sure way in which the workers and females of sabuleli 
could be separated from the typical scabrinodis. The male of sabuleti, 
however, could be distinguished by the longer scape in the American 
specimens. The males of the European representatives of sabuleti 
were "rather variable" as to scape length. If one takes the trouble 
to unravel this remarkable statement, it is apparent that Emery 
could recognize sabuleti only by using the American males, and that 
the intergrading European examples were for all practical purposes 
indistinguishable from the typical scabrinodis. Having defined the 
variety sabuleti, Emery proceeded to set up another, schenki. The 
antennal scape of the male of schenki was very short and its worker 
possessed a lobed scape which had led to confusion of the form with 
lobicornis. Here, as in the case of sabuleti, the definitive characters 
were to be found in the male and, as in sabuleti, the insect occurred 
both in Europe and the United States. No type citation was made for 
schenki because of the earlier descriptions which had confused this 
insect with lobicornis. Emery's interpretation has had a wide accept- 
ance among students of myrmecology. Despite this fact, it cannot 
be regarded as satisfactory. The first doubts in this particular were 
raised by Forel in 1914. In that year he pointed out that the American 
representatives which had been assigned to schenki were not the same 
as those of Europe. He therefore separated the American form as 
the variety emeryana. Very little attention was paid to Forel's 
observation although it held the key to the situation. Most publica- 
tions dealing with our species of Myrmica continued to follow Emery's 
system, although Emery himself threw it over when he published 
the Myrmicine section of the Genera Insectorum in 1921. In that work 
the forms sabuleti and schenki are recorded as coming from Europe 
only. Forel's emeryana had taken care of the New World form mis- 
identified as schenki. The American specimens which Emery had 
considered as representatives of sabuleti were allowed to drop out 
of sight. This insect, which has repeatedly appeared in the literature 
since 1895 under the name sabuleti, was not named until Weber 
described it as the subspecies americana in 1939. 

The remainder of the history of sabuleti and schenki involves a series 
of revisionary studies made on the European forms of Myrmica during 
the period from 1918 to 1931. These studies were not concerned with 
the North American species but they affect them none the less. In 
1918 Bondroit published a monograph on the ants of France and 
Belgium. In this work he presented a drastic revision of Myrmica 
in which he added three new species and accorded specific rank to 
many forms previously considered subspecies or varieties. Both 
sabuleti and schenki were among the forms raised to specific rank. 



CREIGHTON: ANTS OF NORTH AMERICA y 

Bondroit's work was dealt with in a most uncompromising fashion 
by Emery in 1921. His three species were reduced to varietal rank 
and the other changes which he proposed were nullified. Those who 
regard Emery as a taxonomic reactionary will do well to consider that 
extensive subsequent investigation has confirmed Emery's opinion in 
regard to the species which Bondroit described. It is to be regretted 
that less unanimity of opinion has attended his treatment of sabuleti 
and schenki. In 1926 Finzi monographed the European species of 
Myrmica and accorded schenki specific status. He refused, however, 
to make a similar concession in the case of sabuleti. Two years later 
Starcke, who had examined Mienert's types of sabuleti, championed 
specific status for that form. The specificity of both sabuleti and 
schenki was conceded by Santschi when he reviewed the European 
species of Myrmica in 1931. In this paper Santschi was at some pains 
to evaluate the various indices which had been proposed as solutions 
to the Myrmica problem. He discussed the "frontal index" favored 
by Starcke (the ratio of the greatest width of the head through the 
eyes to the maximum divergence of the frontal lobes), his own 
"epinotal index" (the relationship between the infra-spinal incision 
and the lobe at the base of the epinotum) and the old stand-by, the 
length of the antennal scape of the male. Santschi's conclusions are 
as discouraging as they are shrewd. There is scarcely a page on which 
he does not point out the variability and intergradation of diagnostic 
characters. Nearly all the varieties are "relative" and can be deter- 
mined only by statistical studies on long series of specimens. Although 
Santschi was of the opinion that the best criterion of specificity is the 
character of the antennal scape of the male, his studies showed that 
even this characteristic is not always constant. 

In the opinion of the writer Santschi's observations on Myrmica 
are the only ones which hold much hope for the betterment of the 
taxonomy of this desperately difficult group. If the classification of 
Myrmica is to be placed on a reasonable basis, we must place less stress 
on varietal differences and more on adequate specific delimitation. 
In other words, we must give up the idea, to which Forel and Emery 
so faithfully adhered, that scabrinodis consists of a huge complex of 
forms none of which deserve specific status. We shall have to accept 
the fact that when this complex is broken down the species which 
result are less distinct than could be wished and that it is usually 
necessary to augment the lack of good definitive characters in the 
worker caste with characteristics derived from the male. Neverthe- 
less, there appears to be no other possible course, for it can be shown 
on distributional grounds that whatever the members of Emery's 
scabrinodis complex may be, they are certainly not subspecies. As far 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



as the American forms are concerned, there is nothing to be gained 
by continuing to treat them as variants of European species. The 
structural differences that mark most of our representatives which 
have been assigned to the scabrinodis complex are more distinct than 
those which delimit European representatives now treated as sepa- 
rate species. There is no reason to question the propriety of giving 
specific status to sabuleti and schenki, but there is every reason to 
doubt that anything is gained by trying to assign our American forms 
to one or the other of these two species. To do so not only misrepre- 
sents the status of our forms but adds unjustified complications for 
those .who are striving to arrive at satisfactory means for delimiting 
the European species'. It may be admitted that if and when an 
altogether satisfactory taxonomy can be worked out for Myrmica, 
it may be possible to relate some of our forms to European species. 
But until that time we lose rather than gain by attempting such 
relationships. For the above reason I have made no attempt in the 
present work to assign any North American representative to sabuleti 
or to schenki. There are good reasons why americana, hamulata and 
monticola may be treated as species in their own right. I have also 
given specific status to emeryana, although this insect, and its sub- 
species tahoensis, is very close to the European schenki. 

Even so, it must not be thought that this treatment makes it easy 
to handle our forms of Myrmica. It helps to recognize that many of 
the species in this genus differ very slightly. It helps to recognize 
the valuable characteristics which may be found in the male. But 
neither of these realizations eliminate the difficulties inherent in the 
taxonomy of this formidable group. Perhaps the ultimate solution 
lies in the structure of the male genitalia. Dr. Neal Weber, who very 
generously allowed me access to his unpublished monograph on 
Myrmica, believes that this is the case. For the present, however, 
we must deal with this situation as best we can and avoid complicating 
it any further. As things are now it is utterly futile to describe new 
forms of Myrmica from a limited series of workers. We have carried 
one such form for half a century and are no wiser as to its true rela- 
tionships than when it was first described in 1893. I refer to Emery's 
variety detritinodis. This insect was described from three workers 
and, while there is one specimen from the type series (marked as a 
cotype) in the Wheeler Collection at Harvard, it is impossible to 
determine the exact status of the insect. Since so few specimens are 
involved, it is pure conjecture as to what the definitive characteristics 
of detritinodis actually are. This circumstance prevents the associa- 
tion of any male with the insect. Thus Emery's detritinodis may be 
a form of lobicornis, it may belong to schenki, it may have affinities 



CREIGHTON: ANTS OF NORTH AMERICA yi 

with emery ana, or it may be a separate species. To avoid further 
confusion in the case of detritinodis, I propose that it be dropped as 
impossible of exact determination. 

The genus Myrmica is more interesting from a distributional stand- 
point than because of its habits. The habits of our representatives 
are uniformly unspectacular. The insects prefer to nest in soil and 
frequently make use of a covering object above the nest. As a rule 
they are inoffensive ants, but one of them, rubra laemnodis, is pug- 
nacious and can sting severely. The distribution of Myrmica is, on 
the other hand, most interesting. It appears to be the only large 
Holarctic genus which lacks xerophilous or subtropical representatives 
on this continent. A map showing the distribution of Myrmica in 
North America would reveal a widespread occurrence in Canada, with 
northern limits reaching Labrador in the east and Alaska in the west. 
Proceeding southward, one would find a restriction to areas of mod- 
erate to considerable elevation in both the eastern and the western 
United States. The genus is very poorly represented in the southern 
part of the Atlantic Coastal Plain and absent in the Gulf Coast and 
Texas areas. In the western mountains the genus will be found in 
abundance in the subalpine and Canadian zones, in decreasing num- 
bers in the Transition zone and absent in the Sonoran areas at the 
base of the range. There is not a single North American representative 
which can be regarded as a xerophile, although a few forms prefer 
dry nest sites in the Transition zone. There are several other Hoi- 
arctic genera in which a large proportion of the forms behave in a 
similar manner but there is no other member of this group of genera 
which shows this restriction more clearly. If this same characteristic 
were true of all species of Myrmica, it would be possible to conclude 
that the members of this genus are unable to tolerate regions marked 
by protracted periods of high temperature.. But the genus has pro- 
duced a number of species in the tropical portion of southeastern 
Asia, hence this explanation will scarcely apply. The absence of 
tropical and xerophilous species in the New World offers an attractive 
problem for those interested in distributional phenomena. 

From what has been said on previous pages it should be clear that 
the key which follows must carry male characteristics as well as 
those of the worker if it is to be of any service in the case of certain 
species. This makes for a very clumsy sort of key and to reduce the 
complication as much as possible the definitive male characters have 
been included only where they were absolutely necessary. In most 
cases worker structure alone will give satisfactory separation. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Key to the species of Myrmica 

1. Node of the petiole high, distinctly set off from the anterior and posterior 
peduncles and angular at the crest; the ventral surface of the petiole with 
a distinct, obtusely angular impression formed by the junction of the 

anterior and posterior peduncles wheeleri 

Node of the petiole not distinctly set off from the anterior and posterior 
peduncles or, if so, it is low and much rounded above; ventral surface of 
the petiole straight or very feebly convex 2 

2. Outer edge of the frontal lobe feebly convex throughout most of its length 
and fusing with the head without a marked posterior incision; frontal area 
distinct, not crossed by rugae, usually smooth and strongly shining .... 3 
Outer edge of the frontal lobe strongly convex or angular in front, or 
deeply incised behind, or both; frontal area obscured by rugae, never 
completely smooth and shining 4 

3. Antennal scapes extending well beyond the occipital margin; epinotal 
spines at least two-thirds as long as the distance which separates their 

tips rubra subsp. laevinodis 

Antennal scapes barely reaching the occipital margin; epinotum armed 
with two short, triangular teeth rubra subsp. champlaini 

4. Frontal lobes narrow, scarcely or not at all projecting above the antennal 
fossae; the insertions of the antennae exposed when the head is viewed 

from above spatulata 

Frontal lobes strongly projecting out over the antennal fossae; the in- 
sertions of the antennae hidden when the head is viewed from above ... 5 

5. Antennal scape gradually and evenly bent at the base, the upper surface 
never forming a right angle at the bend; the lamina, if present, forming a 
low and inconspicuous ridge at the side of the bend and never prolonged 

onto the upper surface of the scape 6 

Antennal scape suddenly bent at the base, the upper surface forming a 
right angle; lamina always present and of varying shapes but never absent 
from the upper surface of the scape 11 

6. Basal face of the epinotum abruptly depressed below the level of the 

mesonotum; abdomen with numerous coarse punctures 7 

Basal face of the epinotum forming a descending slope with the dorsum 
of the mesonotum which is broken only by the impression at the meso- 
epinotal suture; abdomen with fine punctures 8 

7. Antennal scapes surpassing the occipital margin by an amount equal to 
their greatest thickness; epinotal spines about one and one-half times as 
long as the distance which separates their bases and slightly deflected 
downward; color piceous brown; length 4.0-4.7 mm. (antennal scape of 
the male as long as the following six segments taken together) 

punctiventris 

Antennal scapes barely surpassing the occipital margin; epinotal spines 
only slightly longer than the distance which separates their bases and not 
deflected downward; color brownish yellow; length 3.5-4.0 mm. (antennal 
scape of the male as long as the following two segments taken together) 

pinetorwn 



CREIGHTON: ANTS OF NORTH AMERICA 



8. Lateral margins of the frontal lobes strongly angular, thick and slightly 
but definitely deflected downward (antennal scapes of the male not longer 
than the three following segments taken together and straight at the 

base) 9 

Lateral margins of the frontal lobes rounded, thin and moderately to 
strongly elevated (antennal scape of the male slightly bent at the base 
and as long as the following four or five segments taken together) .... 10 

9. Postpetiole with a shining dorsal area which is largely free from rugae; 

average size of workers 3.5 mm brevinodis subsp. kuschei 

Postpetiole ordinarily covered with rugae, rarely with a dorsal area free 
from rugae but in such cases this area is not shining; average size of 
workers at least 4.5 mm brevinodis 

10. Color orange yellow; epinotal spines slightly less than one-half as long as 

the distance which separates their tips brevispinosa 

Color dark brown; epinotal spines more than one-half as long as the 
distance which separates their tips brevispinosa subsp. discontinua 

11. The bend of the antennal scape with a large, thick lobose lamina which 

extends backward along the basal third of the scape monticola 

The bend of the antennal scape with a small transverse lamina or with a 
thin lamina which surrounds the bend like a collar and does not extend 
backward along the basal third of the scape 12 

12. Ventral surface of the postpetiole seen in profile flat or nearly so and not 
forming a projection in front (antennal scapes of the male as long or longer 
than the following four segments taken together and straight at the 

base) americana 

Ventral surface of the postpetiole seen in profile convex or forming a 
prominent anterior projection which thrusts forward under the anterior 
peduncle (antennal scapes of the male bent at the base or if straight they 
are distinctly shorter than the above) 13 

13. Lamina of the antennal scape forming a high, semicircular welt which 
surrounds the scape at the bend (antennal scape of the male bent at the 
base and usually shorter, never longer, than the three following segments 

taken together) 14 

Lamina of the antennal scape not forming a high, semicircular welt 
(antennal scape of the male straight at the base or if bent its length is 
equal to the following five segments taken together) 15 

14. Lamina of the antennal scape under-cut on its inner face so that the edge 

forms a distinct hook hamulata 

Lamina of the antennal scape without a hook on its inner face 

hamulata subsp. trullicornis 

15. Lamina of the antennal scape small and diagonally transverse on the 
upper surface of the scape but continued as a prominent transparent 
flange along the inner surface of that part of the scape that lies below the 
bend (antennal scape of the male straight at the base and as long as the 

three following segments taken together) emeryana 

Lamina not forming a prominent median flange as above or if a small 
median flange is present the lamina is not transverse on the upper surface 
of the scape 16 



94 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

16. Epinotal spines slightly but distinctly bent downward; thorax reddish 
yellow, head and gaster piceous; (antermal scape of the male straight at 
the base and as long as the following three segments taken together) .... 

emeryana subsp. tahoensis 

Epinotal spines straight; color not as above (antennal scape of the male 
bent at the base and at least as long as the following five segments taken 
together) 17 

17. Antennal lamina encircling the bend of the scape in the form of a spoon- 
like or saucer-like flange (antennal scape in the male abruptly bent at the 
base with the upper surface distinctly angulate at the bend; epinotal spines 
of the male well-developed, the epinotum with prominent rugae) 

lobicornis subsp. lobifrons 

Antennal lamina small and transverse and forming an angular tooth-like 
projection on the inner side of the bend (antennal -scape of the male 
gradually bent at the base and not forming a distinct angle at the bend; 
the epinotal spines of the male reduced to rounded angles, the rugae of 
the epinotum very feeble or lacking) lobicornis subsp. fracticornis 



1. MYRMICA AMERICANA Weber 

M. sabuleti subsp. americana Weber, Lloydia, Vol. 2, p. 144 (1939) 9 9 d" - 
Type loc: Colebrook, Connecticut. Types: M.C.Z., Coll. N. A. Weber. 
Range: eastern Canada and the northeastern United States west to the Rocky 
Mountains. The insect also occurs in the mountains of Utah. 



Although Dr. Weber has treated americana as a subspecies of 
sabuleti, I believe that it should be recognized as a separate species. 
The scape of the male of americana is as long as the following four 
or five segments together and in this respect the insect resembles 
lobicornis. But the scape of the male of americana is straight at the 
base while that of lobicornis is bent. The lobe at the base of the scape 
in the worker of americana is not particularly distinctive and a better 
separatory character seems to be the straight lower border of the 
postpetiole. But, as Dr. Weber has pointed out, there is a certain 
amount of variation even in this latter character, hence for satisfactory 
determination the male should be present. 

Before leaving americana I wish to comment on certain ecological 
characteristics of this insect which seem to need elucidation. In 1944 
Buren expressed the opinion that americana is a 'prairie form'. This 
contention seems to be clearly negated not only by some of Mr. 
Buren's own records but by many of the records coming from the 
very extensive range occupied by americana. For americana not 
only occurs in prairie regions but in several other types of environment 



CREIGHTON: ANTS OF NORTH AMERICA yo 

as well. In the east it has been frequently taken in open woodlands 
and it is my experience that in the Rocky Mountain area it usually 
occurs in foothill canyons at elevations of about 6000 feet. I mention 
this fact because it shows clearly the difficulties of trying to establish 
an 'ecological subspecies' unless one is dealing with the fauna of a 
very limited region. 



2. MYRMICA BREVINODIS Emery 

In the present work so many changes have been made in the 
complex of forms previously assigned to brevinodis that it seems 
advisable to present a single account of them here. M. brevinodis is 
an abundant, widely distributed and highly variable insect and it is 
not surprising that a number of subspecific variants should have 
been attached to it. To date ten described forms have been so treated. 
But if these forms are examined carefully, it is clear that they fall 
into two separate categories. Some of them correspond exactly with 
brevinodis except for very minor differences of color and sculpture. 
These forms possess a male in which the antennal scape is short and 
straight. The second group of forms differs from brevinodis in the 
character of the frontal lobes (see key) and their male has a long scape 
which is curved at the base. It would appear, therefore, that two 
species have been included in brevinodis. To rectify this situation 
I propose to recognize brevispinosa as a separate species. With 
brevispinosa must go decedens, which is a synonym of that species. 
I believe that discontinua is a subspecies of brevispinosa and not of 
brevinodis. The description of discontinua was based primarily on 
the worker but Dr. Weber mentioned a male of this form which was 
'very much like a fracticornis male'. We may assume therefore that 
the male of discontinua shows the long scapes of brevispinosa and 
not the short ones of brevinodis. Of the seven variants which belong 
to brevinodis only one, the Alaskan kuschei, appears to have the 
characteristics of a geographical race. The range of kuschei apparently 
lies at low elevations along the Alaskan seaboard. In those latitudes 
the typical brevinodis occurs at inland stations where the elevation 
is somewhat greater. It is my opinion that the form which Wheeler 
called alaskensis is an intergrade between the typical brevinodis and 
the subspecies kuschei It is unfortunate that it is necessary to synon- 
ymize the varieties canadensis, frigida, subalpina, sulcinodoides and 
whymperi with brevinodis but a study of a large quantity of material 
covering all these variants has shown the impossibility of satisfactory 
separation on either a structural or a distributional basis. In every 



yo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

case the structural distinctions involved consist of exceedingly slight 
differences in sculpture, pilosity or color. Not only are these differ- 
ences remarkably inconsequential but it is only rarely that they hold 
over an entire nest series. As a result this complex of forms presents 
a completely intergrading character which defeats successful handling 
of the several variants. We could, perhaps, do something with the 
group if any of its members showed distinctive distributional charac- 
teristics. But the little of this that exists is of such a general nature 
that it is of no help as a means for delimiting the variants as geo- 
graphical races. In the west the varieties subalpina, sulcinodoides and 
frigida have occasionally been taken together and the first two forms 
regularly occur in the same stations. In eastern Canada frigida and 
canadensis have ranges that are largely coincidental. In 1907 Wheeler 
reported an elevational difference in the case of sulcinodoides and 
subalpina. At that time he believed that subalpina replaced sulcino- 
doides at higher elevations. The much more extensive data which 
Wheeler published ten years later completely contradicted this view 
and showed that the two forms are not marked by any difference in 
their elevational tolerance. My own experience in the field has repeat- 
edly confirmed this fact. I would like to repeat here what was stated 
on an earlier page. It seems much more important to strive for a 
sound concept of the specific characteristics of bremnodis than to 
waste energy on the hopeless task of trying to sort out and name the 
minor fluctuations which occur in it. There follows the synonymy of 
Myrmica bremnodis Emery: 



M . rubra subsp. brevinodis Emery, Zool. Jahrb. Syst., Vol. 8, p. 312 (1895) V cf ; 

Wheeler, Bull. Wis. Nat. Hist. Soc., Vol. 5, p. 74 (1907) 9 9 c?. 
M. rubra subsp. brevinodis var. canadensis Wheeler, Ibid., Vol. 5, p. 76 

(1907) 9 9 cf. 
M. rubra subsp. brevinodis var. frigida Forel, Trans. Ent. Soo. Lond., p. 699 

(1902) 9 ; Wheeler, Bull. Wis. Nat. Hist. Soc., Vol. 5, p. 78 (1907) 9 . 
M. rubra subsp. brevinodis var. subalpina Wheeler, Ibid., Vol. 5, p. 77 

(1907) 9 9 cf. 
M. rubra subsp. brevinodis var. sulcinodoides Emery, Zool. Jahrb. Syst., Vol. 

8, p. 313 (1895) 9 ; Wheeler, Bull. Wis. Nat. Hist. Soo., Vol. 5, p. 75 

(1907) 9 9 d 1 . 
M. rubra subsp. brevinodis var. whymperi Forel, Ann. Soo. Ent. Belg., Vol. 48, 

p. 154 (1904) 9 ; Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 49, p. 215 (1913). 
Type loc: Salt Lake, Utah. Types: none in this country. 
Range: Labrador south to New Jersey and westward through the northern 

United States and Canada to the Pacific northwest and southern Alaska. 

A southern extension in the Rocky Mountain Region extends into the 

mountains of New Mexico. 



CREIGHTON: ANTS OF NORTH AMERICA y/ 

3. MYRMICA BREVINODIS KUSCHEI Wheeler 

M, brevinodis subsp. kuschei Wheeler, Bull. Mus. Comp. Zool., Vol. 61, p. 17 

(1917) 9 9. 
M. brevinodis var. alaakensis Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 52, p. 503 (1917) 9 . 

Typeloc: Ketchikan, Alaska. Types: M.C.Z. 
Range: known only from Alaska. 

Although kuschei was described after alaskensis, it seems admissible 
that the newer name should stand. The variety alaskensis is an 
obvious intergrade between kuschei and the typical brevinodis. Since 
kuschei appears to be a valid geographical race it, and not alaskensis, 
should be the form whose name is retained. 



4. MYRMICA BREVISPINOSA Wheeler 

M. rubra subsp. brevinodis var. brevispinosa Wheeler, Bull. Wis. Nat. Hist. 

Soc., Vol. 5, p. 74 (1907) 9 9 d 1 . 

M. brevinodis var. decedens Wheeler, Ibid., Vol. 5, p. 75 (1907) 9 cf. 
Type loc: Cheyenne Canyon, Colorado (by present designation). 
Types: M.C.Z. 
Range : northern New Mexico to southern Alberta, west to Idaho and eastward 

to Nebraska and North Dakota. 

Although the structural characters which separate brevispinosa 
and brevinodis are more striking in the male than in the worker, there 
would seem to be no doubt that this insect deserves specific status. 
The antennal scape of the male of brevispinosa is certainly no less 
characteristic (see key) than that of other forms which have been 
given specific rank on this basis. The frontal lobes of the worker of 
brevispinosa are entirely different from those of brevinodis (see key). 
The scape of the worker also shows slight but rather significant 
differences. In the worker of brevinodis the curved basal portion of 
the scape is flattened dorso-ventrally and lacks any trace of carinula. 
In brevispinosa the flattening is in a lateral plane and there is a feeble 
but distinct carinula which runs along the side of the curved portion. 
The most obvious difference in the worker is its much shorter epinotal 
spines but this characteristic is unreliable because of the tendency of 
the spines to vary in length. The distribution of brevispinosa is more 
distinct from that of brevinodis than the records seem to indicate. 
The latter species has a wide elevational tolerance which enables it 
to occupy stations in several life zones. The distribution of brevispinosa, 



9s BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

on the other hand, is limited to the transition zone. It prefers to nest 
in gravelly stream bottoms and is one of the most thermophilic 
members of the genus. 

I have synonymized the variety decedens with brevispinosa. Wheeler 
distinguished decedens on the basis of the slightly longer epinotal 
spines of the worker and the slightly longer scape of the male. The 
fluctuation in any large series of specimens of brevispinosa will more 
than include such slight differences. 



5. MYEMICA BEEVISPINOSA DISCONTINUA Weber 

M. brevinodis subsp. discontinua Weber, Lloydia, Vol. 2, No. 2, p. 150 (1939) 9 . 
Typeloc: Florissant, Colorado. Types: M.C.Z., Coll. Weber. 
Range: Newfoundland and Nova Scotia west to the mountains of Colorado 
and Wyoming. 

If I am correct in my view of discontinua, the insect is an eastern 
race of brevispinosa. The ranges of the two forms meet in the Rocky 
Mountain Region and in adjacent states to the east. The reasons for 
transferring discontinua to brevispinosa have been given in the intro- 
duction to brevinodis. 



6. MYRMICA EMERYANA Forel 

M. scabrinodis subsp. schenki var. emeryana Forel, Deutsche Ent. Zeitschr., 

p. 617 (1914) 9 9 cf . 

Type loc: no definite locality cited, by inference North Carolina. 
Types: none in this country. 
Range: Newfoundland to Georgia and west to the Rocky Mountains. The 

western records are comparatively rare. 



Although this insect is closely related to the European schenki 
I believe that it is better to treat it as a separate species, at least until 
the relationship of the American forms to those of Europe is placed 
on a sounder basis than exists at present. The characteristics of the 
scape of the male will readily distinguish emeryana from related 
American species. The scape is straight at the base and as long as 
the following three segments taken together. No other American species 
except brevinodis shows a comparable condition and there is little 
likelihood for confusion between emeryana and brevinodis because of 
the notable differences in the structure of the scape of the worker. 



CREIGHTON: ANTS OF NORTH AMERICA yy 

7. MYRMICA EMERYANA TAHOENSIS Wheeler 

M. scabrinodis subsp. schenki var. tahoensis Wheeler, Proc. Amer. Acad. Arts 

Sci. Boston, Vol. 52, p. 504 (1917) 9 9 d". 

Type loe: Lake Tahoe, California. Types: M.C.Z., Coll. W. S. Creighton. 
Range: British Columbia south to the Sierras of California and the central 

Rockies of Montana and Wyoming. The insect also occurs in the 

mountains of Arizona, Nevada and Utah. 

It is difficult to say exactly where the range of tahoensis meets that 
of the typical emeryana because of the scarcity of the latter insect in 
the Rockies. There is, however, some evidence of intergradation in 
specimens coming from Montana, Utah and eastern Nevada. 



8. MYRMICA HAMDLATA Weber 

M. sabuleti subsp. hamulata Weber, Lloydia, Vol. 2, No. 2, p. 146 (1939) 9 9 cf. 
Type loc: Hayne's Canyon (8000'), Sacramento Mountains, New Mexico. 
Types: M.C.Z., Coll. N. A. Weber. 
Range: mountains of New Mexico, Colorado and Utah. 

The characteristics of both worker and male in hamulata are so 
clearly distinct that there would seem to be no question concerning 
the propriety of treating this insect as a separate species. The peculiar, 
high, thin, hooked flange on the antennal scape of the worker is 
unique. The antennal scape of the male is curved at the base and 
very short. Dr. Weber gives the length of the scape as equal to the 
following two or three segments taken together. It would seem, 
however, that the scape is more often equal in length to the first two 
funicular segments than to the first three. At least this has been the 
case with all the males which the writer has examined. I have taken 
this insect twice in the field. To judge from these two records it 
prefers to nest on upland plateaus at elevations from 7000-8000 feet. 



9. MYRMICA HAMULATA TRULLICORNIS Buren 

M. sabuleti subsp. trullicornis Buren, Iowa State Coll. Jour. Sci., Vol. 18, 

No. 3, p. 281 (1944) 9 9 . 
Type loc: Ames, Iowa. Types: Coll. W. F. Buren, Paratypes: U.S.N.M., 

Coll. Iowa State College, Coll. W. S. Creighton. 
Range: known from stations in Iowa only. 



The exact status of trullicornis is problematical and will remain 
so until a male can be associated with the workers. It has little rela- 



100 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

tionship with americana, in my opinion, although Buren claims to 
have found intergrades connecting the two. The high, thin almost 
vertical flange on the scape of worker of trullicornis certainly suggests 
a relationship with hamulata. But the flange in trullicornis is not as 
extensive as that of hamulata and it lacks the distinct hook which is 
present on the inner face of the flange in hamulata. In this connection 
it is interesting to note that, in one of the two paratypes which Mr. 
Buren very kindly sent me, the mesial edge of the flange is slightly 
impressed at the base. The resulting overhang is far less pronounced 
than the hook in hamulata, indeed it cannot properly be regarded as 
being a hook at all, but at least the same tendency to produce a 
rearward projection from the flange seems to be present in both 
insects. I am ready to admit that to treat trullicornis as a subspecies 
of hamulata involves the hope that its range will subsequently be 
found to extend to the Rockies. But since we have to take the male 
of trullicornis on trust, we may also trust that the distribution will, 
when it is better known, prove in consonance with the above treatment . 

10. MYRMICA LOBICORNIS FRACTICORNIS Emery 

M. rubra subsp. scabrinodis var. fradicornis Emery, Zool. Jahrb. Syst., Vol. 8, 

p. 313 (1895) 9 . 

Type loc: Buffalo, New York (by present restriction). Types: M.C.Z. 
Range: extensively distributed throughout Canada and the northern United 

States. A southern extension follows the Rocky Mountain Highlands into 

northern New Mexico. The insect is rare in the region west of the Rockies 

and seems to be entirely absent on the Pacific slope. 

The status of fracticornis is difficult to evaluate. It can scarcely be 
regarded as an eastern race of lobicornis, for its range in the west is 
almost as extensive as that of lobifrons. But in the west it seems to 
occur at somewhat lower levels than does lobifrons. It would seem, 
therefore, that fracticornis is best regarded as a subspecies whose 
tolerance for lower elevations has enabled it to utilize stations in the 
east as well as in the west, while lobifrons, because of its restriction to 
high elevations, has a distribution limited to the western mountains. 
What appear to be intergrades between the two forms occur in many 
parts of the west. 



11. MYRMICA LOBICORNIS LOBIFRONS Pergande 

M. sabuleti var. lobifrons Pergande, Proc. Acad. Sci. Wash., Vol. 2, p. 521 

(1901) 9. 
M. scabrinodis var. glacialis Forel, Ann. Soc. Ent. Belg., Vol. 48, p. 154 

(1904) 9 ." 



CREIGHTON: ANTS OF NORTH AMERICA 1U1 

M, scabrinodis subsp. lobicornis var. glacialis Wheeler, Proc. Amer. Acad. Arts 
Sci. Boston, Vol. 52, p. 504 (1917) 9 9 d" ; Wheeler, Bull. Mus. Comp. 
Zool. Harvard, Vol. 61, No. 2, p. 21 (1917) 9 . 

Type loc : Metlakahla, Alaska. Types: U.S.N.M., M.C.Z. 

Range: mountains of Colorado and New Mexico north to Alaska. The insect 
also occurs in the mountains of Utah and Arizona. In the southern portions 
or its range lobifrons always occurs at high elevations. In Colorado it is 
rarely found below 8000 feet and usually occurs at much higher levels. 

Wheeler has shown that Pergande's name lobifrons must take 
precedence over Forel's glacialis. 



12. MYRMICA MONTICOLA Wheeler 

M. scabrinodis subsp. schenki var. monticola Wheeler, Proc. Amer. Acad. Arts 

Sci. Boston, Vol. 52, p. 505 (1917) 9 cf . . 

M. sabuleti subsp. nearctica Weber, Lloydia, Vol. 2, No. 2, p. 148 (1939) 9 9 c? . 
Type loe: Beuna Vista, Colorado. Types: M.C.Z. 
Range: central Colorado north to Manitoba and east to North Dakota. 

The short scape of the male and the peculiar flange on the scape 
of the worker clearly mark monticola as a separate species. The scape 
in the male is only a little longer than the two following joints taken 
together but it is straight at the base. This gives a distinction from 
the conditions found in hamulata, which also has a short scape but 
with a curved base. The peculiar lateral flange which extends well 
back along the base of the scape in the worker is unique. 

A singular and very confusing situation has arisen in the case of 
monticola, because of its redescription by W T eber as nearctica. At first 
I was inclined to doubt that this could be the case for, since Dr. Weber 
was working with the Wheeler Collection when he described nearctica, 
it seemed very improbable that the two could be the same. However, 
I now not only believe that the two are the same but also that some 
of the specimens in the second syntype series cited by Weber for 
nearctica are actually a part of the type series of monticola. It may 
be recalled that these specimens were taken by Wheeler at Buena 
Vista, Colorado, the type locality of monticola. The difficulties involved 
in this matter are much more serious than might be supposed for, 
if I am correct as to what happened, they will not be resolved by a 
comparison of the type material of monticola and nearctica at present 
in the Wheeler Collection. During the last years of Dr. Wheeler's 
life his collection was subjected to a great deal of handling. In 1928 
it was transferred from the Bussey Institution to the Museum of 
Comparative Zoology. Later the specimens were taken from their 



1UZ BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY 

original boxes and placed in larger museum cases. Still later the col- 
lection was divided with the American Museum of Natural History. 
The handling of this vast aggregation of specimens was successfully 
accomplished through the care and unremitting effort of Mr. Nathan 
Banks. But in view of the large amount of material involved it is 
not surprising that some slight confusion should have resulted. I know 
from first hand observation that in a few instances type series have 
become mixed. It may be surmised that this was the case with the 
type series of monticola. I believe that Dr. Weber found two distinct 
forms represented in the type series of monticola and that he separated 
the two. I further believe that the specimens which Dr. Weber 
regarded as syntypes of nearctica were actually types or at least a 
part of the type series of monticola. This belief is based on the fact 
that before the Wheeler Collection left the Bussey Institution Dr. 
Wheeler gave me many named specimens from it. Among these were 
representatives of monticola which he had taken at Cheyenne Canyon, 
Colorado, (a part of what is now the second syntype series of nearctica). 
Thus whatever the situation may be at present in the case of the type 
series of monticola and nearctica, I feel reasonably certain that the 
insect which Dr. W r heeler originally treated as monticola is the same 
as that which Dr. Weber has called nearctica. I am aware that much 
of what has been said above is conjectural but until it can be shown 
that the original monticola was something different from nearctica, 
I prefer to treat the latter insect as a synonym of monticola. 

13. MYHMICA PINETORUM W T heeler 

M. punctiventris subsp. pinetorum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 

21, p. 348 (1905) 9. 

Type loc: Lakehurst, New Jersey. Types: M.C.Z. 
Range: southern New England to North Carolina and west to Ohio. 

Although pinetorum has hitherto been regarded as a subspecies of 
punctiventris the two are unusually distinct. Indeed, there is little 
other than the punctuation of the gaster in which the two insects 
exactly correspond. As the ranges of the two are largely coincidental, 
pinetorum cannot be considered as a subspecies. The structural dis- 
tinction which it shows is quite enough to give it specific status. 



14. MYRMICA PUNCTIVENTRIS Roger 

M. punctiventris Roger, Berl. Ent. Zeitschr., Vol. 7, p. 190 (1863) 9 ; Mayr, 
Verb. Zool-bot. Ges. Wien, Vol. 36, p. 450 (1886) 9 9 ; Emery, Zool. 



CREIGHTON: ANTS OF NORTH AMERICA 106 

Jahrb. Syst., Vol. 8, p. 312 (1895) d 1 ; M. R. Smith, Amer. Mid. Naturalist, 

Vol. 37, No. 3, p. 544, pi. 5, fig. 18 (1947) 9 . 
Type loc: North America. Types: none in this country. 
Range: southern New England south to Tennessee and west to Iowa. 



15. MYRMICA RUBRA CHAMPLAINI Forel 
(Introduced) 

M. rubra subsp. champlaini Forel, Mitt. Natur. Mus. Hamburg, Vol. 18, p. 80 

(1901) V. 

Type loc: Quebec, Canada. Types: none in this country. 
Range: known only from eastern Canada. 

The writer regrets that it is necessary to refer to the peculiar series 
of events that have beset the forms of M. rubra which have been 
taken in Canada and the United States. Most myrmecologists have 
let this matter alone, and they have been wise to do so, for the whole 
situation is thoroughly exasperating. In 1900, when Forel was in 
Quebec, he took specimens from a nest 'at the edge of a meadow path 
near the port' of the ant that he named M. rubra champlaini in the 
following year. At this same time he described a second race, M. rubra 
neolaevinodis, from specimens taken from iris rhizomes at the Plant 
Quarantine Station at Hamburg, Germany. These iris rhizomes had 
been shipped to Germany by way of New York, hence Forel cited 
New York as the type locality for neolaevinodis. In 1906 Wheeler 
described a variety of M. rubra, which he called bruesi, from specimens 
taken at Woods Hole, Massachusetts. Since Forel had claimed that 
both champlaini and neolaevinodis are endemic North American ants, 
Wheeler at first took the same view of the variety bruesi. But Wheeler 
was doubtful of this from the start and by 1908 he had reconsidered 
the matter and abandoned Forel's view. D.uring the interval between 
1906 and 1908 Wheeler had taken other specimens in Massachusetts 
which were identical with the European laevinodis. As a result, he 
was prepared to believe that these specimens, and those of the variety 
bruesi as well, had reached this country by importation from Europe. 
Wheeler also felt that this same explanation applied to champlaini, 
and the fact that this insect was taken in close proximity to the docks 
in Quebec favors this view. In the case of neolaevinodis Wheeler 
refused to believe that this insect is a native of North America at all. 
He pointed out that Forel could not be sure that the type series of 
neolaevinodis came from New York and that it seemed peculiar that 
there were no records of this insect, or any form of rubra, from the 
New York area if the insect were actually a native of that region. 



1U4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Wheeler cited his failure to discover neolaevinodis in the New York 
region and I would like to reinforce his experience in this matter with 
my own. Where Wheeler collected in and around New York for six 
years, I have done so for sixteen. Like Wheeler I have never found 
any evidence that rubra occurs in the New York region. 

If Wheeler had held to the position which he advocated in 1908, 
we would have been well on the way to a satisfactory solution of this 
problem. Both laevinodis and champlaini could have been treated as 
introduced forms and neolaevinodis could have been dropped from 
the list of North American ants. Instead, Wheeler reversed himself 
completely in 1917 by including all three forms in the list of native 
eastern species which formed a part of his study on the mountain 
ants of western North America. I cannot explain this extraordinary 
reversal and I certainly cannot subscribe to it. For that matter I do 
not think that Wheeler himself did so. I consider that the inclusion 
of the three forms in the above list was accidental and not an indication 
that Wheeler had changed his opinion as to their status in our ant 
fauna. Except for the fact that I have treated the variety bruesi 
as a synonym of laevinodis, I propose, in this volume, to adhere to the 
view which Wheeler published in 1908. Under this plan champlaini 
and laevinodis will be treated as introduced forms and neolaevinodis 
will be dropped from the roster of North American ants. 



16. MYRMICA RUBRA LAEVINODIS Nylander 
(Introduced) 

M. laevinodis Nylander, Act. Soc. Sci. Fennicae, Vol. 2, p. 927, pi. 18, fig. 5 
(1846) 9 9 cf ; Mayr, Verb. Zool-bot. Ges. Wien, Vol. 5, p. 402 (1855); 
Nylander, Ann. Sc. Nat. Zool. (4), Vol. 5, p. 78 (1856); Meinert, Natur. 
Afh. Dansk. Vid. Selsk (5), Vol. 5, p. 51 (1861); Mayr, Europ. Formicid, 
p. 64 (1861); E. Andre, Spec-. Hym. Europe, Vol. 2, p. 316, pi. 21, figs. 1-8 
(1882); Ruzsky, Formic. Imp. Rossici, Vol. 1, p. 655, fig. 165 (1905) 9 9 cf ; 
Donisthorpe, Brit. Ants, p. 110 (1915) 9 9 cf . 

M. rubra subsp. laevinodis Forel, Fourmis Suisse, p. 76 (1874) 9 9 cf; Emery, 
Deutsche Ent. Zeitschr, p. 170, fig. 3, 4 (1908) 9 9 cf ; Forel, Fauna Insect 
Helvet. Hym. Form., p. 28 '(1915); Emery, Bull. Soc. Ent. Ital., Vol. 47, 
p. 119, fig. 17, 21a (1916) 9 9 cf . 

M. rubra laevinodis var. bruesi Wheeler, Psyche, Vol. 13, p. 38 (1906) 9 ; 
Wheeler, Jour. Econ. Ent., Vol. 1, p. 338 (1908) 9 . 

Type loo: Denmark. Types: none in this country. 

Range: (in the United States) eastern Massachusetts. 

Although this ant is now firmly established in eastern Massachu- 
setts, there seems to be little evidence that it is spreading out of that 



CREIGHTON: ANTS OF NORTH AMERICA iuo 

area. In 1928 the insect was abundant in Forest Hills and outlying 
parts of Boston. Unlike most other species of Myrmica, it has a 
powerful and painful sting and does not hesitate to use it. 

17. MYRMICA SPATULATA M. R. Smith 

M. schenki var. spatulata M. R. Smith, Ann. Ent. Soe. Amer., Vol. 23, p. 566 

(1930)9 9. 

Type loc: Starkville, Mississippi. Types: Coll. M. R. Smith, M.C.Z. 
Range: Mississippi to Illinois. 

Smith described this insect as a variety of schenki. The male 
appears to be unknown but, even in its absence, there are so many 
outstanding characters shown by the worker that it may be given 
specific status. The very large, spatulate lamina on the antennal 
scape which gave this insect its name is exceedingly striking when 
fully developed. Unfortunately the lamina is prone to wide variation 
in size. For this reason I have utilized the equally striking and much 
more constant structure of the frontal lobes (see key) as a means for 
recognizing this species. 

18. MYRMICA WHEELERI Weber 

M. wheeleri Weber, Lloydia, Vol. 2, p. 150 (1939) 9 9 cf. 

Type loc: Mt. Lemmon and Mt. Stratton, Arizona. Cotypes: M.C.Z., Coll. 

N. A. Weber. 
Range: known only from type material. 

As Weber pointed out in his original description of wheeleri, this 
insect resembles brevispinosa in many respects. It differs from brevi- 
spinosa in its slightly down-curved spines and in the very smooth 
and shining frontal area. The structure of the petiole is, however, 
the outstanding feature of wheeleri (see key). In particular the deep, 
angular impression in the ventral surface of the petiole separates this 
species from all other North American representatives of Myrmica. 



Genus MANICA Jurine 
(Plate 15, figures 1-4) 

In a paper published in 1947 Dr. Neal Weber has proposed to accord 
Manica generic status. The writer fully agrees with this view and for 
this reason the following paragraph, which was written before Dr. 
Weber's proposal appeared, has been left in its original form. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



As far as the North American representatives of Manica are con- 
cerned there is little to suggest intergradation with the members of 
the genus Myrmica. It must be admitted, however, that the European 
Manica rubida is less distinct than might be wished. This species 
usually possesses an epinotum in which the angle between the basal 
and declivious faces is provided with low, flange-like projections. 
These projections are certainly not spines but, on the other hand, 
there are several representatives of Myrmica in which the epinotal 
spines are reduced to angles. If the unarmed epinotum were the only 
feature which distinguishes Manica from Myrmica it would scarcely 
be possible to defend generic status for Manica. But there are other 
differences which together produce an insect quite distinct from those 
belonging to the genus Myrmica. The mesonotum in Manica is 
somewhat strangulate, which gives the thorax the appearance of a 
thick-waisted hourglass when seen from above. In Myrmica the im- 
pression at the mesoepinotal suture is usually much less extensive and 
largely limited to the upper portion of the thorax. Because of this the 
thorax of Myrmica does not have an hourglass appearance when seen 
from above. In Manica each mandible bears a prominent terminal 
and subterminal tooth, with the remainder of the masticatory margin 
unarmed or bearing only fine denticles. In Myrmica the mandible 
usually bears a second subterminal tooth and the rest of the masti- 
catory margin bears a row of well-developed denticles which increase 
in size toward the apex. The node of the petiole in Manica is evenly 
rounded above. This condition rarely occurs in Myrmica, where the 
node is marked by an angular crest. The sculpture of Manica is much 
less rugose than that of Myrmica. This is particularly noticeable on 
the thorax where the rugae occur as parallel lines. In Myrmica the 
thoracic rugae (and usually those elsewhere as well) are strongly 
reticulate, even in the smoother forms. The few males of Manica 
which the writer has seen all have very long and well-developed 
mandibles. The ocelli are set well back on the head, the laterals lying 
at the level of the occiput. This gives the head of the Manica male 
a totally different appearance from that of the male of Myrmica. For 
in the male of Myrmica the mandibles are small (often strap-like) and 
the ocelli are set in front of the occipital level. 

The nomenclatorial tangle concerned with the genus Manica has 
been needlessly involved. In 1911 Wheeler published a list of the 
genera and subgenera of ants and designated a type for each group in 
which there had been no previous selection of a genotype. In this list 
Jurine's Manica appeared as a synonym of Myrmica. Wheeler desig- 
nated Formica rubida Latreille as the genotype of Manica. There is 
no reason to question this choice, since it had been granted for years 



CEEIGHTON: ANTS OF NORTH AMERICA 1U7 

that Jurine's Manica rubida was identical with Latreille's species 
bearing the same name. In 1914, however, Wheeler revised his opinion 
concerning the status of rubida and the North American species allied 
to it, and proposed to give the group subgeneric rank under the name 
Oreomyrma. As he designated rubida as the subgenotype of Oreo- 
myrma, one must suppose that he had forgotten his previous desig- 
nation of this same species as the genotype of Manica, Earlier that 
same year (1914) Forel had published the description of a species 
which he called calderoni. Forel regarded this insect as belonging to 
a new subgenus of Aphaenogaster, for which he proposed the name 
Neomyrma. In the following year Wheeler was able to show that 
calderoni is a synonym of bradleyi. But while Wheeler's specific name 
bradleyi had precedence, his subgeneric name Oreomyrma did not. 
Wheeler, therefore, replaced his subgeneric name with Forel's Neo- 
myrma and shifted the subgenotype to bradleyi. There is no telling 
how much longer this nomenclatorial juggling would have continued 
had not Emery cut through the tangle and restored the rightful name, 
Manica, to the group. 

With the exception of parasitica, which may prove to be a temporary 
social parasite, there is little out of the ordinary in the habits of our 
species of Manica. The colonies are never very populous and rarely 
contain more than a few hundred individuals. The nests of bradleyi 
seem to be larger than those of the other species. It is possible that 
aldrichi may prefer to nest in open woods but, if so, this is an exception 
to the general rule that these insects select fully exposed nest sites. 
Most of the species build obscure nests in soil that is often very harsh 
and gravelly. Only bradleyi seems to prefer to nest under stones. 
According to Mallis (1941) this species sometimes constructs a regular 
low cone or disc around the nest entrance. I believe, however, that 
this must be regarded as exceptional. I have seen so many nests of 
bradleyi without any trace of excavated material above them that it 
is impossible to believe that this species regularly constructs a mound 
above the nest. 

The key which follows differs considerably from that given in 
Wheeler's 1914 study of Manica. Wheeler's key was based largely on 
distinctions of color. Wliile some of our species of Manica can be 
recognized by their characteristic color, it seems best to subordinate 
such color differences to the structural features which mark the species. 
These are not only more reliable than color but, since they are perfectly 
satisfactory as key characters, there is no reason why they should not 
be used. It seems well to note that the figure which Wheeler gave for 
mutica in 1914 shows the postpetiole of that insect without a trace of 
ventral projection. Such individuals occur in almost every colony but 



108 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

this is not the form of the postpetiole most commonly encountered. 
Much more often the postpetiole of mutica shows a small, rounded, 
ventral projection which occupies the same position as the more 
prominent protuberances found in aldrichi and hunteri. In mutica, 
however, this projection is not only much smaller but it does not 
project forward as do those of the other two species. 

Key to the species of Manica 

1. Postpetiole with a very prominent, conical, ventral protuberance which 

projects forward beneath the posterior peduncle of the petiole 2 

Postpetiole without a ventral protuberance or with a small, rounded, 
ventral projection which does not extend forward beneath the posterior 
peduncle of the petiole 3 

2. Antennal scape just reaching the occipital border; color clear yellow. . . . 

aldrichi 

Antennal scape surpassing the occipital border by an amount equal to its 
greatest thickness; color deep reddish orange hunteri 

3. Posterior face of the node of the petiole in large part smooth and shining; 

at least the head and gaster piceous brown '...,... .4 

Posterior face of the node of the petiole sculptured and opaque; the entire 
insect dull yellow or orange mutica 

4. Thoracic sculpture feeble, the surface moderately to strongly shining; color 

uniform piceous brown parasitica 

Thoracic rugae coarse and prominent, the surface scarcely shining; head 
and gaster piceous brown, the thorax clear yellow bradleyi 

1 . MANICA ALDRICHI (Wheeler) 

Myrmica (Oreomyrma) aldrichi Wheeler, Psyche, Vol. 21, p. 120, fig. 1 b 

(1914) 9. 

Typeloc: Moscow, Idaho. Types: M.C.Z. 
Range: mountains of northern Idaho to the Cascade Range in Washington 

and Oregon. 

Although this species is by no means rare its distribution seems to 
be very discontinuous. The writer has encountered it but once in the 
field. On that occasion the nest was situated in fairly open pine woods 
at an elevation of about 3000 feet. 



2. MANICA BRADLEYI (Wheeler) 

Myrmica bradleyi Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 77 (1909) 9 ; 
Myrmica (Oreomyrma) bradleyi Wheeler, Psyche, Vol. 21, p. 119, fig. 1 e 
(1914) 9 ; Wheeler, Ibidem, Vol. 22, p. 50 (1915) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA iuy 

Aphaenogaster (Neomyrma) caldermi Forel, Rev. Suisse Zool., Vol. 22, p. 275 

(1914) 9. 

Type loc: Alta Meadow, Tulare Co., California. Types: M.C.Z. 
Range: upland meadows of the California Sierras at elevations of 8500-9000 

feet. 

3. MANICA HUNTERI (Wheeler) 

Myrmica (Oreomyrma) hunteri Wheeler, Psyche, Vol. 21, p. 121, fig. 1 c (1914) 9 . 
Type loc: Madison River, Beaver Creek, Montana (7500') Types: M.C.Z. 
Range: mountains of southwestern Montana to the ranges of northeastern 
Nevada. 

The preference of hunteri for nest sites at considerable elevations is 
well marked. In the southern part of its range the insect usually nests 
at elevations around 8000 feet. It seems never to descend below 7000 
feet even in the northern part of its range. 



4. MANICA MUTICA (Emery) 

Myrmica mulica Emery, Zool. Jahrb. Syst., Vol. 8, p. 311 (1895) 9 . 
Myrmica (Oreomyrma) mutica Wheeler, Psyche, Vol. 21, p. 119, fig. 1 d 

(1914) 9 9 d". 
Myrmica (Monica) mutica M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 544, pi. 5, fig. 19 (1947) 9 . 

Type loc: Denver, Colorado. Types: none in this country. 
Range: eastern slopes of the Rocky Mountains from central Colorado to 

southern Alberta and thence west to the Sierras in California and the 

Pacific Coast in Washington and southern British Columbia. 

The range of mutica is far larger than that of any of our other species 
It also seems to have a somewhat more continuous distribution, which 
is probably due to the fact that it occurs at lower levels than do some 
of the other species. In Colorado it is rarely found above 5000 feet 
and seems to prefer foot hill areas, where the nests are constructed in 
fully exposed situations and usually in coarse gravelly soil. While the 
sting of mutica is exceedingly painful, the insect is not particularly 
aggressive and will usually avoid using its sting unless the nest is 
disturbed. 



5. MANICA PARASITICA (Creighton) 

Myrmica (Manica) parasitica Creighton, Psyche, Vol. 41, No. 4, p. 185 

(1934) 9. 
Type loc: Polly Dome, Yosemite National Park, California (8600'). 



Ill) BULLETIN" : MUSEUM OF COMPARATIVE ZOOLOGY 

Types: M.C.Z., Coll. W. S. Creighton. 
Range: known only from type material. 
Host: M. bradleyi. 

It is unfortunate that no additional material of parasitica has been 
secured for we need more information on this species. There can be 
no question that the insect is parasitic in the nests of bradleyi but as 
to whether this relationship is a permanent one or a matter of tempo- 
rary social parasitism cannot be determined at present. 



Genus PoGONOMYRMEX Mayr 
(Plate 16, figures 1-4) 

In the present volume it has so often been necessary to discuss 
taxonomic problems connected with genera and subgenera that it is a 
pleasure to note that this is unnecessary in the case of Pogonomyrmex. 
Since 1868, when Mayr first set up the genus, there has been good 
agreement on the group. This is not to say that Pogonomyrmex lacks 
taxonomic problems but these are on a specific or infraspecific level. 
We may, therefore, go directly to the habits of these interesting ants. 

The ants which belong to Pogonomyrmex have always attracted an 
unusual amount of popular interest. Some of this, it must be admitted, 
is of a rather gruesome character. There is a persistent belief that in 
the days when the West was wilder than it is now, Indians would 
sometimes stake out a human victim across a nest of Pogonomyrmex. 
If this was actually done, it would be hard to imagine a more ex- 
cruciating death. The sting of most species of Pogonomyrmex is 
excessively painful. It is not a localized reaction, like that of a bee 
sting, but one which spreads along the lymph channels and often 
causes intense discomfort in the lymph glands of the axil or groin long 
after the original pain of the sting has ceased. 

In a more cheerful vein there is the celebrated story of Lincecum 
and his 'ant rice' (1862). It was Lincecum's contention that Pogo- 
nomyrmex cultivates a species of grass which it harvests and stores in 
the nest over winter and replants the following spring. Many of 
Lincecum's observations were correct and it is unfortunate that the 
deductions which he drew from them were not more cautious, for he 
almost had his story right. However his erroneous view found eminent 
sponsors, among them Charles Darwin, and this gave to it a standing 
which was a long time in being dispelled. It was not until W'heeler 
began his studies on these ants at the beginning of the present century 
that the matter was put on a sound basis. 



CREIGHTON: ANTS OF NORTH AMERICA 111 

The habits of most of our species of Pogonomyrmex appear to be 
fairly uniform. Although the size of the colony and the shape of the 
mound are subject to considerable variation, there is good reason to 
suppose that all the species depend largely on the seeds of plants for 
their main dietary staple. At certain seasons the seeds are brought to 
the nest in such quantities that a large surplus accumulates in the 
nest chambers. As Wheeler has shown (1910) the workers of Pogo- 
nomyrmex do not damage the seeds to prevent them from germinating. 
During periods of unusual wetness a considerable portion of the stored 
seeds may sprout. The ants remove these seedlings and discard them 
on the kitchen midden which surrounds the nest. Many of the dis- 
carded seedlings take root and there thus grows up around the nest 
an "ant garden" whose origin so sadly misled Lincecum. It may be 
doubted that any member of this genus is limited to an exclusively 
graminicolous diet. Like most ants they will take insect food when it 
is available. But seeds can be easily stored while insect food cannot. 
This is a matter of first importance to a group whose life is spent in 
desert areas where the active period for most plants and insects is 
limited to a very short season. The seed gathering propensities of 
Pogonomyrmex may, therefore, be less an outcome of a special fondness 
for seeds than the result of a life spent under climatic conditions which 
severely limit the period for successful foraging. 

Many of the ants of the genus Pogonomyrmex possess, on the under 
surface of the head, elaborate fringes of hairs which Santschi has called 
'psammophores' and Wheeler 'ammochaetae'. There are two sets of 
such hairs, one on the inner surface of the majidibles, the other running 
along each side of the head. The mandibular hairs are somewhat 
shorter and more even in length than the gular hairs and, when the 
mandibles are closed, they form a sort of a grating below the mouth- 
parts. The gular hairs are graded in length with very long ones behind 
and much shorter ones near the insertion of the mandibles. All the 
gula hairs are directed diagonally inward toward the midline of the 
head but it is only the long rear hairs which come anywhere near 
meeting at the midline. The function of these hairs is a matter which 
has given rise to widely different explanations. In 1907 Wheeler 
published a paper in which this subject was discussed. He concluded 
that the ammochaetae serve as cleaners for the strigils of the forelegs, 
which are themselves cleaning organs used to rid the antennae of dust 
particles. According to Wheeler the strigils of xerophiles are much 
more apt to become clogged with dust than those of ants which live 
in less arid places. This added need for cleansing the strigils would 
explain the frequency of ammochaetae in various desert-dwelling 
genera. Wheeler was able to observe that the workers of Pogo- 



BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 



nomyrmex draw the strigils through the ammochaetal hairs and he 
interpreted this to mean that the insects were cleaning the strigils "in 
much the same way that we clean a comb with threads". This simile 
is not particularly convincing. The hairs of the strigils are very much 
finer than those of the ammochaetae and so closely set that there is 
virtually no space between them. The strigils might conceivably be 
cleansed by rubbing them against the ammochaetal hairs but, if so, 
the process would be more like drawing a fine-tooth comb along a 
manilla rope. In 1909 Santschi, using artificial nests, was able to 
observe the use of the mandibular ammochaetae in the case of Messor 
barbarus. The carrying of small quantities of dry sand was facilitated 
because of the support offered by the hairs below the mandibles. 
Santschi attempted to extend this observation to the gular ammo- 
chaetae and claimed that the much larger masses of dampened sand 
which the insects were able to carry were supported at the rear by the 
gular hairs. This statement seems very questionable, since Santschi's 
figures show the compacted particle of damp sand held well forward 
in the mandibles and, as he himself admitted, such large lumps of 
sand could only be carried if they were wet enough for the particles 
to stick together. Since his main thesis, like that of Wheeler, was 
intended to show why ammochaetae are characteristic of xerophiles 
and not of other ants, this admission is detrimental to his theory. It 
seems to the writer that the most reasonable explanation for the gular 
ammochaetae is that they offer protection to the delicate mouthparts 
of the ants from blowing sand. Their position would serve such a 
purpose admirably and this would also explain the absence of such 
structures in non-xerophilous genera which must excavate just as much 
soil and get just as dirty in the process as do the xerophiles. 

The North American representatives of Pogonomyrmex have been 
repeatedly keyed. Mayr (1887), Wheeler (1902) and Olsen (1934) 
have all published keys covering this group of species. In every case 
these keys have used as their major split the presence or absence of 
spines on the epinotum. This seems such an obvious difference that 
it may appear ill-advised to question its value. The writer is con- 
vinced, nevertheless, that it cannot be successfully employed as a 
major division of the group. There are several species of Pogo- 
nomyrmex in which the epinotal armature is highly variable. Speci- 
mens coming from the same nest may have well-developed epinotal 
spines or a completely unarmed epinotum. It would, therefore, be 
necessary to have such species appear twice in the key if epinotal 
armature is used as a major split. This difficulty can be largely 
avoided by using epinotal armature in a more strategic fashion. It is 
often an excellent means for distinguishing between species, even 



CKEIGHTON: ANTS OF NOKTH AMERICA lid 

though it is unsuitable as a major key character. The following key 
has been constructed on the basis of the above considerations and, as 
a result, differs considerably from existing keys. 



Key to the species of Pogonomyrmex 

1. The flange-like projections at either side of the insertion of the petiole 
always rounded behind ; lower surface of the head with a row of very long, 

coarse hairs at either side (Subgenus Pogonomyrmex) 2 

The flange-like projections at either side of the insertion of the petiole 
strongly angular or tooth-like; the lower surface of the head without hairs 
or with scattered hairs which are not arranged in two lateral rows (Sub- 
genus Ephebomyrmex) 23 

2. Worker caste strongly polymorphic, the major worker with a dispro- 

portionally enlarged head (southeastern states) badius 

Worker caste not polymorphic, the size usually rather constant but when 
size differences occur the largest workers do not have disproportionally 
enlarged heads (southwestern states) 3 

3. Clypeal border with a deep, semicircular impression, the bottom of which 

almost reaches the level of the frontal lobes sancti-hyadnthi 

Clypeal border straight or with a broad, shallow concavity, the bottom 
of which lies anterior to the level of the frontal lobes 4 

4. The antennal scapes in repose failing to reach the occipital border by an 
amount at least as great as the length of the first two funicular segments 

together 5 

The antennal scapes in repose failing to reach the occipital border by an 
amount no greater than the length of the first funicular joint If 

5. Epinotum always armed with two erect, well-developed spines (> 

Epinotum without spines, usually rounded but in some cases with denti- 
form angles present apache 

6. Occipital margin, seen from above, covered with rugae throughout 7 

Occipital margin, seen from above, with the striae and rugae largely 
confined to the middle third, the lateral portions bearing piligerous 
punctures and sometimes feebly shagreened but not rugose or striate. . 10 

7. Entire thorax coarsely reticulo-rugose, the cephalic rugae becoming dis- 
tinctly reticulate on the occipital corners; length 5 mm huachucanus 

Thorax not reticulo-rugose throughout; epinotum and often the meso- 
notum as well with even, subparallel, transverse rugae; the rugae on the 
occipital corners never distinctly reticulate; length of the largest worker 
at least 6.5 mm. and usually more 8 

8. Cephalic rugae fine and close-set with the interrugal sculpture largely 

absent except for a few coarse punctures 9 

Cephalic rugae coarser and more widely spaced with the interrugal 
sculpture consisting of rugules and granulations as well as coarse punctures 

barbatus subsp. rugosus 

9. Color uniform, ferrugineous red barbatus 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGI 



Head and thorax blackish brown, the gaster black with the base of the 
first segment marked with yellow barbatus subsp. fuscatus 

10. Dorsum of the pronotum without distinct rugae or with delicate rugae 

which are not heavy enough to dull the shining surface 11 

Dorsum of the pronotum with strong, transverse rugae which extend en- 
tirely across it and make the surface dull or feebly shining 

desertorum subsp. ferrugineus 

11. Epinotal spines slightly tapered from base to tip desertorum 

Epinotal spines not tapered, as slender at the base as at the tip 

desertorum subsp. tenuispina 

12. Interrugal sculpture of the head consisting of feeble punctures which do 

not obscure the shining surface 13 

Interrugal sculpture of the head consisting of very dense, distinct 
punctures, the surface opaque or very feebly shining 16 

13. Epinotum always armed with two erect, well-developed spines . . subnitidus 
Epinotum without spines, usually rounded, rarely angular 14 

14. Node of the petiole slender, distinctly longer than its anterior peduncle 

longinodis 

Node of the petiole shorter and thicker, not longer than its anterior 
peduncle 15 

15. Color uniform, clear yellow, the gaster scarcely or not at all darker than 

the head and thorax californicus 

Gaster in large part black, notably darker than the yellow head and 
thorax, petiolar nodes often brown californicus subsp. estebanius 

16. Postpetiole largely or entirely covered with transverse rugae; ventral 

tooth of the postpetiole well-developed subdentatus 

Postpetiole with the transverse rugae, when present, confined to the 
posterior third of the node, the remainder of the node granulose or densely 
punctate; ventral tooth of the postpetiole poorly developed or absent. . 17 

17. Basal third of the first gastric segment opaque, densely punctate or very 

heavily shagreened salinus 

Basal third of the first gastric segment moderately to strongly shining, 
the surface at most very feebly shagreened 18 

18. Posterior face of the node of the petiole with rough irregular rugae in 

addition to the dense punctures 19 

Posterior face of the node of the petiole punctate or shagreened only . . 20 

19. Epinotal spines shorter than, or at least no longer than, the distance which 
separates their bases, the spines distinctly tapered from base to tip. ... 

occidentalis subsp. comanche 

Epinotal spines distinctly longer than the distance which separates their 
bases, the spines scarcely tapered over most of their length . . . occidentahs 

20. Epinotal spines usually well-developed, only rarely reduced to dentiform 

angles ; 

Epinotum never armed with spines, usually rounded, rarely slightly 
angular 22 

21. Interrugal sculpture of the thorax heavy and dense, often largely obscuring 
the rugae, the thoracic surface completely opaque; head and thorax 



CREIGHTON: ANTS OF NORTH AMERICA 



ferrugineous; length 4.5 mm owyheei 

Interrugal sculpture of the thorax dense but not obscuring the rugae, the 
thoracic surface feebly shining; head and thorax yellowish red; length 
7 mm hindleyi 

22. Node of the petiole seen from behind only slightly higher than wide with 
a distinct nipple-like projection in the middle of the crest; surface of the 
thorax dull or very feebly shining; color rich, ferrugineous red 

maricopa subsp. barnesi 

Node of the petiole seen from behind distinctly higher than wide, the 
crest bluntly angular in the middle but usually without the central nipple; 
surface of the thorax moderately shining; color yellow or orange . . maricopa 

23. The anterior ridge or welt which closes the antennal fossa produced into 
a broadly triangular tooth which projects forward at the side of the 

median lobe of the clypeus 24 

The anterior ridge or welt which closes the antennal fossa not produced 
into a tooth pima 

24. Basal half of the first gastric segment sculptured and largely opaque; 
postpetiole heavily punctate and almost completely opaque 

imberbiculus subsp. townsendi 

Basal half of the first gastric segment without sculpture, the entire segment 
smooth and shining; postpetiole feebly punctate and moderately shining 

imberbiculus 



Subgenus POGONOMYRMEX Mayr 

1 . POGONOMYRMEX APACHE Wheeler 

P. apache Wheeler, Psyche, Vol. 9, p. 329 (1902) 9 . 

Typeloc: Ft. Davis, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 

Range: western Texas and southern Arizona. At present there appear to be 
no published records from New Mexico but the insect must certainly occur 
in the mountain regions in the southern part of that state. 



2. POGONOMYRMEX BADIUS (Latreille) 

Formica badia Latreille, Fourmis, p. 238, pi. 11, figs. 71 A-D (1802) 9 9. 
P. badius Emery, Zool. Jahrb. Syst., Vol. 8, p. 310 (1895); Wheeler, Amer. 

Naturalist, Vol. 36, p. 99, fig. 8 (1902) 9 ; Wheeler, Psyche, Vol. 9, p. 392 

(1902) 9 ; Olsen, BulL.Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 499, 

pi. 1, figs. 1, 2 (1934) 9 . 

Atta badius Lepeletier, Hist. Nat. Hym., Vol. 1, p. 174 (1836). 
Myrmica transversa F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 129 (1858) 9 . 
Pogonomyrmex transversa Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 359 

(1886); Mayr, Ibid., Vol. 37, p. 610 (1887) 9 . 
Atta crudelis F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 170 (1858). 



llo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Myrmica crudelis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 760 (1862) 9 ? . 
Pogonomyrmex crudelis Mayr, Ann. Soc. Natur. Modena, Vol. 3, p. 170 (1868); 

McCook, Agri. Ant., p. 311, pi. 10, 11 (1879); Mayr, Verh. Zool-bot. Ges. 

Wien, Vol. 37, p. 610 (1887) 9 . 

? Myrmica brevipennis F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 130 (1858) d\ 
? Pogonomyrmex brevipennis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 359 

(1886); Mayr, Ibid., Vol. 37, p. 610 (1887) <?. 
Type loc: Carolina. Types: none in this country. 
Range: Florida to North Carolina and west into Mississippi. 

The single record of badius from New Jersey is a puzzling one. The 
presence in the pine barrens of a number of southern forms which are 
found with badius elsewhere would indicate that badius might occur 
there. If so it must be exceedingly rare. Although Dr. Wheeler 
collected intensively in the pine barrens he was never able to find 
badius there and this has been the experience of the writer as well. 
It also seems to be absent in the stretch of similar country which runs 
southward along the eastern shore of Virginia. 

The nests of badius usually consist of flattened craters with an 
irregular central entrance. The species is unusually docile for a 
Pogonomyrmex but if they are aroused to the point of using their 
stings, the pain is more severe than that of any other species known 
to the writer. 



3. POGONOMYKMEX BARBATUS (F. Smith) 

The treatment herein proposed for the barbatus complex runs 
counter to that accepted by most myrmecologists for the past seventy- 
five years. This course requires justification. It is unfortunate that 
a review of the situation involves so much intricate material. The 
complicated and lengthy discussion which follows is necessary if we 
are to clear away certain time-hallowed misconceptions which have 
obscured the true character of the barbatus complex. 

In Olsen's 1934 monograph of the genus Pogonomyrmex the 
classical version of the barbatus complex is strictly maintained. His 
arrangement, identical with that given by Emery in the Genera Insect- 
orum, is as follows : 

P. barbatus F. Smith (1858) 
var. fuscatus Emery (1895) 
var. marfensis Wheeler (1902) 
var. molefaciens Buckley (1860) 
var. nigrescens Wheeler (1902) 
subsp. rugosus Emery (1895) 



CREIGHTON: ANTS or NORTH AMERICA 11 / 

Tile taxonomy of a group whose two oldest representatives share 
descriptive honors between Smith and Buckley may well be suspect. 
There can be no question that this circumstance has contributed to 
the present unsatisfactory state of the complex but no one familiar 
with subsequent developments can justly claim that either Smith or 
Buckley should be saddled with the full responsibility. Smith's 
original description of barbatus was based upon a female taken in 
Me.dco. The insect was assigned to the genus Myrmica and, because 
of the worthless description, it remained unrecognizable for a number 
of years. For this reason Buckley cannot be blamed that he failed to 
realize that the insect which he described in 1860 as Myrmica (Atta) 
molefaciens was a synonym of barbatus. In 1868 Mayr set up the 
genus Pogonomyrmex. At that time he described several new species 
in the genus and transferred to it Latreille's badius and Smith's 
barbatus. It is by no means clear how Mayr was able to make the 
transfer in the case of barbatus, for he did not see the type in the 
British Museum until nearly twenty years later. About 1870 Mayr 
began to receive from Norton, a contemporary and friend of Buckley, 
considerable material coming from the western United States. A part 
of this material appears to have been identified by Buckley and may 
actually have contained cotypes of some of Buckley's species. In 
any case it is evident that when Mayr examined the British Museum 
collection in 1886 he was in position to speak with authority concerning 
the identity of barbatus and molefaciens. With his usual modesty 
Mayr attributed the synonymy to McCook. This procedure was, 
perhaps, more polite than wise. In 1876 McCook had written to 
Forel and sent him specimens which he said were identical with 
Buckley's molefaciens. In reply Forel had declared the insect to be 
identical with Smith's barbatus. McCook naturally accepted this 
opinion without question but, as will be subsequently shown, Forel 
had no clear idea of the exact nature of barbatus at that time and his 
surmise, although correct, was largely guesswork. In addition to 
the specimens which he had from McCook, Forel possessed others, 
apparently taken by Saussure in Mexico. In comparing the two lots 
Forel noted that the Texas specimens sent him by McCook were 
ferrugineous, while those coming from Mexico were notably darker 
in color. This color difference was observable in all the castes. With- 
out any attempt to verify the correctness of his assumption Forel 
proceeded to associate the dark specimens with the typical barbatus, 
which thus became the "Mexican harvester", while the ferrugineous 
specimens were given varietal status under Buckley's name molefaciens 
and christened the "Texas harvester". If Forel had taken the trouble 
to read Smith's description of barbatus, he might have discovered that 



118 BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

the color of the insect is clearly described as ferrugineous. Mayr, of 
course, realized this and when, in 1887, he described the male of 
barbatus, he noted that the insect is of a clear, yellow color. In view 
of the fact that Mayr was the only myrmecologist who had been 
able to compare authentic material of molefaciens and barbatus, it is 
curious that so little attention was paid to his opinion. Instead, other 
workers in the field have elected to follow the lead of Forel and, in 
so doing, have involved themselves in a hopeless tangle. In 1895 
Emery described two new variants in the complex. Both of these, 
the variety fuscatus and the subspecies rugosus, were dark forms but, 
since rugosus showed marked sculptural peculiarities, only the first 
form made trouble. The color characteristics of fuscatus appeared 
so similar so those of Forel's "typical barbatus" that Emery found it 
necessary to redefine the latter form. It emerged from this overhaul 
as an insect having a black head and thorax and red petiolar nodes 
and gaster. Thus Emery was able to distinguish fuscatus as being 
brownish red with the gaster brown. In 1902 Wheeler attacked the 
barbatus problem and added two more varieties. Both of these were 
dark but, because Wheeler accepted Emery's definition of the char- 
acteristics of the "typical barbatus", he was able to satisfy himself 
of the validity of the varieties nigrescens and marfensis. Additional 
consideration led Wheeler to attempt a further clarification of the 
nature of the "typical barbatus". In 1914 he noted that this insect 
is "distinctly smaller and perhaps a little darker than the workers 
of the variety molefaciens. . . . ". Additional differences were found 
in the case of the sexual forms. 

From the above it is clear that the typical barbatus is an extraor- 
dinarily protean form or else that the principal criterion for the 
recognition of this form in the past has been that the specimens have 
been taken in Mexico. I propose to return to the position advocated 
by Mayr and regard the typical barbatus as identical with the ferru- 
gineous variant molefaciens. Contrary to the supposition published 
by Forel in the Biologia Centrali Americana, the range of this insect 
is not primarily confined to Texas. It is by far the most abundant 
form in Mexico and has a southern range greatly in excess of any of 
the dark variants. Of the latter I regard only two as valid. The 
variety fuscatus is an upland form which has a distribution not unlike 
that of the typical barbatus. The subspecies rugosus is a northern 
variant which, apparently, does not enter Mexico. The varieties 
nigrescens and marfensis appear to me to be synonyms of fuscatus, 
although the former may be an intergrade between fuscatus and 
rugosus. There follows the synonymy of Pogonomyrmex barbatus 
F. Smith: 



CREIGHTON: ANTS or NORTH AMERICA 119 

Myrmica barbata F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 130 (1858) 9 . 
P. barbatus Mayr Ann. Soo. Natur. Modena, Vol. 3, p. 170 (1868); Mayr, 

Verb. Zool-bot. Ges. Wien, Vol. 20, p. 971 (1870) 9 ; McCook, Agri. 

Ant. (1879) 9 9 cf; Mayr, Verb. Zool-bot, Ges. Wien, Vol. 37, p. 610 

(1887) 9 d". 
Myrmica molefaciens Buckley, Proc. Acad. Nat. Sci. Phila., p. 445 (1860) 9 ; 

Lincecum, Proc. Acad. Nat, Sci. Phila., p. 323 (1886); McCook, Ibid., 

p. 299 (1877). 

P. molefaciens Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 365 (1886). 
P. barbatus var. molefaciens Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 42 

(1886); Emery, Zool. Jahrb. Syst, Vol. 8, p. 308 (1895) 9 9 of ; Wheeler, 

Amer. Naturalist, Vol. 36, p. 98 (1902); Wheeler, Psyche, Vol. 9, p. 391 

(1902) 9 ; Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 497 

(1934) 9. 

Typeloc: Mexico. Types: none in this country. 
Range: southern Kansas and Oklahoma through western Texas into Mexico 

and southwestward through New Mexico and Arizona. The insect also 

occurs sporadically in extreme southern Utah. 

In the United States barbatus prefers nest sites in areas of com- 
paratively low elevation. It is only in the southern part of its range 
that it is commonly found at elevations of more than 3000 feet. 



4. POGONOMYRMEX BARBATUS FXJSCATUS Emery 

P. barbatus v&T.fuscatus Emery, Zool. Jahrb. Syst., Vol. 8, p. 309 (1895) 9 9 ; 

Wheeler, Amer. Naturalist, Vol. 36, p. 98 (1902); Wheeler, Psyche, Vol. 9, 

p. 391 (1902) 9 ; Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, 

p. 497 (1934) 9 . 
P. barbatus Wheeler, Amer. Naturalist, Vol. 36, p. 91, 98, fig. 4 (1902) 9 ; 

Wheeler, Psyche, Vol. 9, p. 390 (1902) 9 ; Olsen, Bull. Mus. Comp. Zool. 

Harvard, Vol. 77, No. 8, p. 496, pi. 2, fig. 2 (1934) 9 . 
P. barbatus var. nigrescens Wheeler, Psyche, Vol. 9, p. 389 (1902) 9 ; Olsen, 

Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 479 (1934) 9 . 
P. barbatus var. marfensis Wheeler, Amer. Naturalist, Vol. 36, p. 98 (1902) 9 ; 

Wheeler, Psyche, Vol. 9, p. 391 (1902) 9 ; Olsen, Bull. Mus. Comp. Zool. 

Harvard, Vol. 77, No. 8, p. 497 (1934) 9 . 
P. barbatus subsp. curvispinosus Cole, Ent. News, Vol. 47, No. 5, p. 120 

(1936) 9. 

Typeloc: Colorado. Types: none in this country. 
Range: western Texas, New Mexico, southern Colorado and Arizona and 

south into Mexico. 

Superficially considered the range of the subspecies fuscatus appears 
to coincide rather closely with that of the typical barbatus. There is, 
however, a marked preference for higher elevations in the case of 



iZO BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

fuscatus which keeps the two separated. In western Texas fuscatus 
usually occurs at elevations of 4000 feet or above while the typical 
barbatus rarely reaches such an elevation within our borders. This 
circumstance contributes to the more discontinuous distribution of 
fuscatus which is well represented only in mountainous areas. In 
several parts of its range fuscatus comes in contact with the northern 
race rugosus. Where the two forms meet inter grades are produced. 
I regard Cole's curvispinosus and Wheeler's marfensis as such inter- 
grades. Wheeler's nigrescens appears to be a straight synonym of 
fuscatus. 

5. POGONOMYRMEX BARBATDS RUGOSUS Emery 

P. barbatus subsp. rugosus Emery, Zool. Jahrb. Syst., Vol. 8, p. 309 (1895) 9 cf; 

Wheeler, Amer. Naturalist, Vol. 36, p. 98 (1902) 9 ; Wheeler, Psyche, 

Vol. 9, p. 391 (1902) 9 ; Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, 

No. 8, p. 497 (1934) 9 . 

P similis Olsen, Ibid., p. 512, pi. 6, fig. 2 (1934) 9 . 
Type loc: San Jacinto, California. Types: none in this country. 
Range: northwestern Texas, northern New Mexico, southwestern Colorado, 

southern Utah, Arizona and California. 

Olsen records rugosus only from Arizona and California but this is 
certainly incorrect. While the insect is rather sporadic in Texas it 
is fairly abundant in northern New Mexico and southern Utah. It 
appears to enter Colorado only in the extreme southwestern part of 
the state. 

The species described by Olsen as similis is a synonym of rugosus. 
The types of similis have a very striking, dull surface, quite unlike 
that of rugosus. An examination of these types convinced the writer 
that this peculiar dull appearance is due to encrusted soil particles. 
A thorough cleaning of one type specimen proved the correctness of 
this supposition. P. similis is nothing but a small and very dirty 
worker of rugosus. 

The nests of rugosus are usually built in stony soil in open deserts. 
They consist of a gravel disc without any superstructure. There is 
usually a considerable cleared area around the disc. 



6. POGONOMYRMEX CALIFORNICUS (Buckley) 

In the opinion of the writer the constitution of the species californicus 
has been highly unsatisfactory. Much of this difficulty seems attribut- 
able to the fact that the exact nature of the typical californicus is 



CEEIGHTON: ANTS OF NORTH AMERICA 



conjectural. For many years, however, it has been agreed that the 
insect that Buckley described as californicus is a comparatively small 
species (about 6 mm.) with a completely unarmed epinotum, a feeble 
sculpture and a uniform yellow coloration. This being the case there 
would seem to have been very little reason for assigning to californicus 
some of the forms that have been treated as subspecies or varieties of 
it. There is, for example, little to justify Forel's association of hindleyi 
with californicus. It is true that the epinotal armature of hindleyi 
is variable but in those specimens where spines are not present the 
epinotum is marked by dentiform angles. The sculpture of hindleyi 
is notably heavier than that of californicus. Indeed, about the only 
thing that Forel seems to have been able to find to relate the two 
species is a similarity in the shape of the head. To accord separate 
specific status to hindleyi is no particular problem. The burden rests 
with those who are seeking reasons for the retention of this insect as 
a variant of californicus. Similar considerations apply in the case of 
maricopa and its western subspecies barnesi. This species is notably 
larger and stockier than californicus, with a characteristic dense 
cephalic sculpture, distinctly bulkier petiolar nodes and a stronger 
impression at the mesoepinotal suture. These differences are con- 
siderably more pronounced than those which separate certain species 
having epinotal spines and it is hard to avoid the impression that the 
principal reason for making maricopa a subspecies of californicus has 
been its lack of epinotal spines. In the opinion of the writer maricopa 
should certainly have specific rank and it has been treated as a species 
in the present volume. 

The status of the two remaining forms of californicus which occur, 
in the United States is much more difficult to evaluate. The variety 
estebanius and the subspecies longinodis both present problems which 
seem insoluble on the basis of our present knowledge. There is con- 
siderable reason why estebanius might be regarded as nothing more 
than a color variety 'of californicus. In 1914 Wheeler accorded sub- 
specific rank to this form but the observations which he cited at that 
time are singularly confusing. Thus Wheeler claims that estebanius 
'averages a little smaller in all three phases than the typical califor- 
nicus'. Yet the measurements which he presented for the male and 
female of estebanius are larger than those which he gave for the typical 
californicus. I cannot see that there is any significant difference in 
the size of the two forms, nor can I see that the differences which 
Wheeler described in the structure of the node of the petiole are 
sufficiently constant to give good separation. On the other hand, 
the two forms are readily separable on the basis of color and in this 
instance the color difference appears to be correlated with distribution. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



It is possible, therefore, to treat estebanius as a geographical race of 
californicus although, for reasons which have been explained on a 
subsequent page, the matter needs additional verification in the field. 

The situation concerning longinodis is exceedingly puzzling. When 
Emery described longinodis in 1895 he had specimens which will have 
to be regarded as authentic material of the typical californicus. It was 
Emery who finally realized the nature of Buckley's species. Previously 
Mayr had considered it a synonym of badius. In 1895 Emery also 
had type specimens, or at least authentic specimens, of Pergande's 
estebanius. This has enabled us to be certain of the sculptural charac- 
teristics of the insect which Emery treated as the typical californicus. 
Since he found only a color difference between californicus and este- 
banius, it is clear that Emery's typical californicus was the concolorous, 
lightly sculptured insect that has since been accepted as the exemplar 
of Buckley's species. But while there has been good agreement on the 
typical californicus there has been no such agreement in the case of 
longinodis. Emery's original description of longinodis cited a number 
of differences which separate this insect from the typical californicus. 
The petiolar joints are slenderer, with the postpetiole longer than high 
and the petiole with a node which is pointed above and longer than its 
anterior peduncle. The sculpture is feebler with both the striae (or 
rugae) and the sculpture between them much weaker. The petiolar 
nodes are punctate but lack striae. It is significant that Emery re- 
garded these differences as great enough to warrant subspecific status 
for longinodis. In 1902 Wheeler used several of Emery's distinctions 
almost verbatim in his keys. The same is true of the key in Olsen's 
.1934 monograph. I have no fault to find with such usage but I would 
like to point out that the specimens identified as longinodis by Wheeler 
will not check with the key characters given for that subspecies. It 
is true that in these specimens the node of the petiole is much longer 
than that of californicus but the node is not distinctly pointed above 
and, despite its length, it is not longer than the anterior peduncle, for 
that part is also greatly elongated. The cephalic sculpture is notably 
heavier than that of the typical californicus. It may be noted that all 
of the specimens identified as longinodis by Wheeler come from stations 
in New Mexico and Texas. The type locality of longinodis is the 
'Colorado Desert' in California. 

It is the opinion of the writer that the true longinodis has been 
taken only once and that Emery's types may be the only material of 
this insect at present in a collection. At least I have never seen any 
specimens that agree with Emery's description and there seem to be 
no published records that anyone has since taken this insect in Cali- 
fornia. This leads to a very awkward situation as regards the eastern 



CREIGHTON: ANTS or NORTH AMERICA iZ6 

specimens which have previously been treated as longinodis. Until we 
know more about longinodis it seems impossible to be certain as to 
whether the specimens coming from New Mexico and Texas are an 
eastern race of longinodis or a separate species. There is, of course, 
the possibility that they are actually the same as Emery's longinodis 
but this seems very unlikely. I find it impossible to believe that such 
a meticulously careful worker as Emery could have made the de- 
scriptive errors which such a contention would imply. It seems to me 
that the best course at present is to attempt no formal recognition of 
these specimens until their relationship to longinodis is more clearly 
understood. At the same time, I believe that it is necessary to raise 
longinodis to specific rank. The eastern specimens and the typical 
californicus occur in the same stations without intergradation and it is 
safe to assume that the same situation occurs in California. It is 
impossible to consider longinodis as a subspecies of californicus under 
such circumstances. There follows the synonymy of P. californicus 
Buckley: 

Myrmica californica Buckley, Proc. Ent. Soc. Phila., p. 336 (1868) 9 . 

P. californicus Emery, Zool. Jahrb. Syst., Vol. 8, p. 311 (1895); Wheeler, Psyche, 
Vol. 9, p. 391 (1902) 9 ; Wheeler, Ibid., Vol. 21, p. 153 (1914) 9 9 rf; 
Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 499, pi. 2, 
fig. 3 (1934) 9 . 

P. badius Mayr, Ann. Soc. Nat. Modena, Vol. 3, p. 170 (1868); Mayr, Verh. 
Zool-bot. Ges. Wien, Vol. 20, p. 971 (1870) 9 ; Mayr, Ibid., Vol. 37, p. 610 
(1887) 9 (nee Latreille). 

Typeloc: California. Types: none known to exist. 

Range: southern California to western Texas and south into Mexico. The 
range of californicus apparently does not extend north of the New Mexico- 
Colorado border but there is one interesting record of the insect from St. 
George in extreme southern Utah. 



7. POGONOMYRMEX CALIFORNICUS ESTEBANIUS Pergande 

P. badius subsp. estebanius Pergande, Proc. Cal. Acad. Sci. (2), Vol. 4, p. 33 

(1893) 9. 
P. californicus var. estebanius Emery, Zool. Jahrb. Syst., Vol. 8, p. 311 (1895); 

Wheeler, Amer. Natural, Vol. 36, p. 98 (1902); Wheeler, Psyche, Vol. 9, 

p. 391 (1902) 9 . 
P. californicus subsp. estebanius Wheeler, Psyche, Vol. 21 , p. 154 (1914) 9 9 d" ; 

Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 499 (1934). 
Typeloc: Calmalli Mines, San Estaban, Lower California. Types: U.S.N.M. 
Range: deserts of southern Arizona, southern California and Lower California. 



lz4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The geographical relationship of estebanius is a peculiar one which 
at present cannot be explained in an altogether satisfactory way. In 
the much more extensive range of the typical californicus there are 
areas on the east, the north and the west where pure stands of the 
insect occur. This is not the case with estebanius, except in the 
Imperial Desert of California. In southern Arizona estebanius and 
californicus are both present and this seems true also of the western 
portion of the Mojave Desert. It would be much more in keeping with 
the concept of estebanius as a geographical race if it showed a more 
distinctive range of its own. Unless I am very much mistaken, this 
range lies in northwestern Mexico. A better knowledge of the distri- 
bution of estebanius in the provinces of Sonora and Chihuahua should 
show a southern extension of estebanius alone, comparable to the 
northern range of the typical californicus. For the occurrence of 
estebanius in many parts of the Imperial Desert, an area which is not 
utilized by californicus, seems to indicate that it is much more thermo- 
philous than californicus. 

8. POGONOMYEMEX DESEETOEUM Wheeler 

P. desertorum Wheeler, Psyche, Vol. 9, p. 387 (1902) 9 ; Emery in Wytsman 
Genera Insectorum, Fasc. 174, pi. 1, fig. 8 (1921) 9 ; Olsen, Bull. Mus. 
Comp. Zool. Harvard, Vol. 77, No. 8, p. 496, pi. 3, fig. 2 (1934) 9 . 

Type loc: Presidio County, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. 
Creighton. 

Range: western Texas and southeastern New Mexico. 



9. POGONOMYEMEX DESEETOEUM FEERTJGINETJS Olsen 

P. desertorum var. ferruginous Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, 

No. 8, p. 60S (1934) 9 . 

Type loc: Tucson, Arizona. Types: M.C.Z., A.M.N.H. 
Range : southern Arizona to southern New Mexico. 

In the opinion of the writer, the principal difference which dis- 
tinguishes ferrugineus from the typical desertorum is the heavy, trans- 
verse, pronotal sculpture of the former insect. In the typical desertorum 
the dorsum of the pronotum is often very feebly sculptured and the 
rugae, if present, are longitudinal except on the neck of the pronotum, 
where they may be transverse. In ferrugineus the entire pronotum is 
covered with coarse, transverse rugae. The color differences and the 
distinctions based upon spine length which Olsen cited seem to be too 
variable to be of much separatory value. It seems clear th&tferrugineiis 



CREIGHTON: ANTS OF NORTH AMERICA izo 

should be considered as a geographical race for it intergrades with the 
typical form in southwestern New Mexico. 



10. POGONOMYRMEX DESERTORUM TENUISPINA Forel 

P. desertorum var. tenuispina Forel, Bull. Soe. Vaud. Sci. Nat., Vol. 50, p. 269 

(1914) 9. 

Type loo: uncertain, probably Lower California. Types: none in this country. 
Range: apparently confined to Lower California. 

In describing this insect Forel noted that the types had been re- 
ceived from Pergande in the United States ("Resu des Etats Unis de 
M. Pergande"). It has, therefore, been customary to regard tenuispina 
as occurring within our borders. But so far all specimens referable to 
this subspecies have come from Lower California and it is probable 
that the insect does not occur in the United States. 



11. POGONOMYRMEX HINDLEYI Forel 

P. calif ornicus var. hindleyi Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 50, p. 270 
(1914) 9 ; Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 499 
(1934) 9. 

Type loc: Escondido, California. Types: none in this country. 

Range: California, Arizona and New Mexico. 



It is to be regretted that no type specimens of hindleyi are present 
in American collections. It will be necessary to examine the types of 
this insect before we can be certain of its exact status. Even without 
this, however, it is reasonably certain that Forel was in error when he 
assigned hindleyi to californicus. This matter has been discussed in 
the introduction to californicus. At the present time it seems best to 
treat hindleyi as a separate species. It is certainly not related to 
californicus on the basis of structure, nor will its distribution allow it 
to be considered as a geographical race of that species. It should be 
borne in mind, however, that when hindleyi is better known it may 
prove to be a race of some other species. In the opinion of the writer 
it is rather closely related to subdentatus and it is interesting to note 
that both forms show the same variability in epinotal armature. The 
epinotum may bear only small triangular denticles or fully developed 
spines as long as those of occidentalis. These extremes and intermediate 
conditions connecting them are normally found within most nest series. 



126 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

12. POGONOMYEMEX HUACHUCANUS Wheeler 

P. huachucanus Wheeler, Psyche, Vol. 21, p. 151 (1914) 9 ; Olsen, Bull. Mus. 

Comp. Zool. Harvard, Vol. 77, No. 8, p. 497, pi. 4, fig. 1 (1934) 9 . 
Type loc: Miller Canyon, Huachuca Mts., Arizona. Types: M.C.Z., 

A.M.N.H., Coll. W. S. Creighton. 
Range: various mountain ranges in southern Arizona. 



13. POGONOMYBMEX LONGiNODis Emery 

P. californicus subsp. longinodis Emery, Zool. Jahrb. Syst., Vol. 8, p. 311 
(1895) 9 ; Wheeler, Amer. Naturalist, Vol. 36, p. 99 (1902); Wheeler, 
Psyche, Vol. 19, p. 392 (1902) 9 ; Wheeler, Ibid., Vol. 21, p. 155 (1914); 
Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 499 (1934) 9 . 

Type loc: Colorado Desert, California. Types: none in this country. 

Range: California to western Texas. 

As I have shown in the introduction to californicus, the taxonomy 
of longinodis is at present in a very unsatisfactory state, with con- 
siderable differences present in the material which has been assigned 
to this species. The key carried in this volume has been designed to 
take care of specimens showing the characteristics which Emery cited 
for longinodis. The specimens of longinodis coming from western Texas 
and New Mexico would key down to maricopa, from which they would 
differ in the longer and much more slender petiolar node and its thin, 
elongate, anterior peduncle. The petiole of these specimens is about 
one and a half times as long as that of maricopa. 

The nest of longinodis is seldom surmounted by a cone. The exca- 
vated material is usually scattered about with little attempt to form 
a superstructure above the nest. In this respect the insect differs from 
californicus and maricopa both of which heap the excavated material 
above the nest. 



14. POGONOMYRMEX MARICOPA Wheeler 

P. californicus subsp. maricopa Wheeler, Psyche, Vol. 21, p. 155 (1914) 9 9 ; 
Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 500 (1934) 9 . 

Type loc: Alamogordo, New Mexico. Types: M.C.Z., A.M.N.H. 

Range: deserts of southeastern California to western Texas. The insect ap- 
pears to be more abundant in southern Arizona than in any other part 
of the range. 

Anyone who has compared the distribution of maricopa and cali- 
fornicus will appreciate the fact that the ranges of the two insects in 
the United States coincide with remarkable exactness. It is true that 



CREIGHTON: ANTS OF NORTH AMERICA iz< 

californicus occurs in the coastal area of California, where maricopa 
is not present, but this seems to be the only significant difference. 
From the Mojave Desert of California to El Paso, Texas the two 
occur in the same stations with no difference of elevation which might 
separate them. This being true, it is quite impossible to contend that 
maricopa is a subspecies of californicus on distributional grounds alone. 
It may be admitted that the two insects are closely related but it would 
seem that there is quite enough structural difference in the two to 
justify specific status for maricopa. In point of fact the two may be 
separated at a glance for the deeper color and notably larger and 
bulkier stature of maricopa gives it an appearance quite unlike that of 
californicus. However, there are a number of other differences. The 
cephalic sculpture of the two insects is totally unlike. That of maricopa 
is heavy and dense with the surface completely opaque. The thoracic 
sculpture of maricopa is also heavier than that of californicus, although 
there appears to be more variation in this latter characteristic. In 
addition, the epinotum of maricopa is more angular than that of 
californicus with the mesoepinotal suture usually more distinctly 
impressed. The petiole and postpetiole of maricopa are notably more 
bulky than those of californicus. The differences listed above will 
apply equally well to maricopa subsp. barnesi. 

15. POGONOMYRMEX MARICOPA BARNESI M. R. Smith 

P. californicus subsp. barnesi M. R. Smith, Ann. Ent. Soc. Amer., Vol. 22, 
p. 546 (1929) 9 ; Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, 
p. 499 (1934) 9 . 

Type loo: 20 miles northwest of Phoenix, Arizona. Types: Coll. M. R. 
Smith, M.C.Z. 

Range: central Arizona west to the Imperial and Mojave Deserts. 

Although the range of barnesi appears to be lapped by the much 
more extensive range of the typical maricopa, it seems to occur at 
lower elevations than does the typical form. I have seen intergrades 
between barnesi and maricopa which were taken at Needles, California 
by Dr. A. C. Cole. 



16. POGONOMYKMEX OCCIDENTALS (Cresson) 

Myrmica occidentalis Cresson, Proc. Ent. Soc. Phila., Vol. 4, p. 426 (1856) 9 9 . 
P. occidentalis Cresson, Trans. Amer. Ent. Soc., Vol. 7, p. 22 (1879); McCook, 

Honey. Ants and Occident Ants, p. 123-162, fig. 107-112 (1882) 9 9 cf ; 

Mayr, Verh. Zool-bot. Ges. Wien, Vol. 37, p. 610 (1887); Emery, Zool. 



12s BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Jahrb. Syst., Vol. 8, p. 310 (1895); Wheeler, Amer. Naturalist, Vol. 36, 

p. 92, 98, fig. 5 (1902) 9 ; Wheeler, Psyche, Vol. 9, p. 391 (1902) 9 ; 

Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 498, pi. 4, 

fig. 2 (1934) 9 ; M. R. Smith, Amef. Mid. Naturalist, Vol. 37, No. 3, 

p. 544, pi. 5, fig. 20 (1947) 9 . 

Myrmica seminigra Cresson, Proc. Ent. Soc. Phila., Vol. 4, p. 427 (1865) c?. 
P. opaciceps Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 971 (1871) 9 . 
P. occidentalis subsp. ruthveni Gaige, Proc. Bio. Soc. Washington, Vol. 27, 

p. 93 (1914) 9 9 cf. 
Typeloc: Colorado. Types: A.N.S.P. 
Range: southern North Dakota to central Oklahoma and west to Nevada, 

the deserts of eastern Oregon and arid areas in eastern Washington and 

southern British Columbia. 

Although the area outlined above embraces the main range of 
occidentalis, there are scattered records from stations outside it. Thus 
occidentalis has been reported from western Iowa and Missouri. I 
believe, however, that it may be doubted that occidentalis has been 
able to establish itself in either state. A line drawn from eastern South 
Dakota to central Oklahoma would rather closely approximate the 
eastern limit of the range of occidentalis. It has been my experience 
that the eastern boundary of the range of occidentalis is an unusually 
abrupt one. I have repeatedly observed that the insect is extremely 
rare in eastern Kansas but about twenty or thirty miles west of Salina 
one suddenly comes upon areas where the colonies are fully as abundant 
as they are anywhere in the range. The southern end of the range of 
occidentalis is rather irregular, due to the preference of this species for 
nest sites at increasing elevation in southern stations. Thus through 
New Mexico and Arizona the range of occidentalis follows elevated 
table lands or low mountain ranges. Since it has been taken in the 
mountains of southern Arizona, there is every reason to suppose that 
occidentalis occurs in the highlands of Sonora, although at present 
there seem to be no Mexican records for the insect. 

The conspicuous, conical mound nests made by occidentalis are a 
characteristic part of many western landscapes. The mounds are 
usually about two feet across at the base and perhaps a foot high. The 
openings are at the base of the mound. There is usually a large, 
circular, cleared disc surrounding the mound. 



17. POGONOMYRMEX OCCIDENTALIS COMANCHE Wheeler 

P. occidentalis subsp. comanche Wheeler, Psyche, Vol. 9, p. 392 (1902) 9 . 
P. comanche Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 498 
(1934) 9 nec.pl 3, fig. 1; nee. Wheeler, Psyche, Vol. 21, p. 156(1914) 9 cf 1 . 
P. occidenlalis subsp. utahensis Olsen, Ibid., p. 509 (1934) 9 9 cf. 



CREIGHTON: ANTS OF NORTH AMERICA izy 

Type loc: Milano, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: western Texas to Arizona. 

There have been so many errors made in regard to the taxonomy 
of comanche that it is hard to know where to begin their rectification. 
One may as well start with the curious error which occurs in Olsen's 
monograph. The thorax of comanche bears short but very distinct 
epinotal spines. In the figure which Olsen presented as comanche the 
thorax is shown as spineless. Whatever Olsen's figure of comanche 
may be, it is certainly not comanche. A much more serious difficulty 
has arisen from Wheeler's attempt to associate females and males with 
the worker of comanche. Unless I am very much mistaken, this associ- 
ation was incorrect and it has been the cause of much subsequent 
misunderstanding. As may be recalled, Wheeler originally described 
the worker of comanche as a subspecies of occidentalis in 1902. Twelve 
years later he raised the insect to specific rank on the basis of differ- 
ences in the epinotal armature of the male and female and the man- 
dibular structure of the male. The insect which Wheeler regarded as 
the male of comanche had narrow mandibles with a transverse masti- 
catory margin bearing three or four teeth. There are some extraordi- 
nary observations in Wheeler's 1914 discussion of comanche. For 
example Wheeler states: 

"In the worker comanche the thoracic dorsum is distinctly more 
rounded and arched in profile than in the worker occidentalis, and the 
epinotal spines are longer (italics mine, W.S.C.) both in the worker and 
female but especially in the latter." 

The distinction which Wheeler originally used to separate comanche 
from occidentalis was the fact that comanche has much shorter epinotal 
spines. This fact can be verified by an examination of the worker 
types. It cannot be supposed that this peculiar inconsistency is due 
to Wheeler having written longer when he meant shorter for he also 
noted that the male of comanche has longer epinotal teeth than that 
of occidentalis. W T e thus have the unusual situation of a worker with 
short epinotal spines associated with sexual forms in which the epinotal 
spines or teeth are unusually long. The matter becomes even more 
incomprehensible when it is considered that in the worker of occidentalis 
the spines are much longer than those of comanche and yet the sexual 
forms of occidentalis have much shorter epinotal spines than those of 
the males and females which Wheeler assigned to comanche. 

In my opinion the sexual forms which Wheeler assigned to comanche 
cannot possibly belong to that form. I base this opinion on the 
characteristics of the sexual forms of the insect which Dr. Olsen de- 
scribed as occidentalis subsp. utahensis. The type material of utahensis 
was taken by the writer in Zion National Park in 1932. The males 



loU BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

of this insect have a tuberculate epinotum without teeth. Their 
mandibles have an oblique masticatory margin with five to six teeth. 
They thus agree with the occidentalis male and not at all with the 
insect which Wheeler regarded as the male of comanche. Dr. Olsen 
was, therefore, correct in relating them to occidentalis rather than to 
Wheeler's male of comanche. Unfortunately the worker of utahensis 
cannot, in my opinion, be separated from that of comanche. Olsen 
attempted to separate the two on the basis of an excised clypeus in 
occidentalis and a straight one in comanche. I am sorry to say that this 
difference is of no value. The amount of incision of the clypeus varies 
in both forms. In a series of four cotypes of comanche which I have 
before me, one has an almost straight clypeal edge, two have a moder- 
ately incised clypeal edge and the fourth specimen has a clypeal 
incision fully as deep as any found in occidentalis. I have made every 
effort to discover some difference by which the worker of utahensis 
can be separated from that of comanche but I have been unable to 
find one. 

But if, as I believe, comanche and utahensis are the same, it will be 
necessary to revaluate the status of comanche. The differences which 
separate this insect from occidentalis are its shorter epinotal spines and 
very slightly more convex thorax. It would, therefore, seem that 
Wheeler was right when he treated comanche as a subspecies of occi- 
dentalis in 1902. The range of comanche runs from western Texas to 
Arizona. Since there are not more than a half a dozen published records 
for this insect, it is impossible to get a very satisfactory picture of its 
distributional characteristics. But it would seem that the records for 
comanche come from lower elevations than do those of occidentalis. In 
general the latter form occurs at elevations of 5000 feet or more in the 
southern part of its range. Por this reason in southern New Mexico 
and Arizona occidentalis is usually confined to mountain valleys or 
high plateaus. From the little we know of comanche the insect prefers 
low plains or canyon bottoms where occidentalis rarely occurs. Hence 
there is no reason why comanche may not be regarded as a southern, 
low-level subspecies of occidentalis. As Wheeler has pointed out the 
nests of comanche are usually not surmounted by conical mounds but 
by a low and rather irregular crater. 



18. POGONOMYBMEX OWYHEEI Cole 

P. occidentalis subsp. owyheei Cole, Amer. Mid. Naturalist, Vol. 19, No. 1, 

p. 240 (1938) V 9 . 
Type loc: Indian Cove, Hammet, Idaho. Types: Coll. A. C. Cole, Coll. 

W. S. Creighton. 
Range: known only from type material. 



CREIGHTON: ANTS or NORTH AMERICA lol 

At first sight the small size of this curious little species seems to 
ally it to huachucanus. Actually, however, the two insects have little 
in common. The scapes of owyheei are notably longer than those of 
huachucanus and the thoracic sculpture of the two insects is entirely 
different. Dr. Cole treated owyheei as a subspecies of occidentalis and 
its structure certainly relates it to the group of species to which 
occidentalis belongs. In 1942 Dr. Ernst Mayr showed that the distri- 
bution of owyheei is such that it can scarcely be a subspecies of occi- 
dentalis and it may be added that it shows enough structural difference 
from occidentalis to warrant specific status on the latter basis as well. 
According to Cole, owyheei makes small crater nests in pure sand. 

19. POGONOMYRMEX SALINUS Olsen 

P. salinus Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 510, 

pi. 5, fig. 3 (1934) 9 . 

Typeloc: Soda Springs, Bridgeport, California. Types: M.C.Z. 
Range: known only from the type material. 

20. POGONOMYRMEX SANCTI-HYACINTHI Wheeler 

P. sancti-hyacinthi Wheeler, Psyche, Vol. 9, p. 388 (1902) 9 . 

Type loc: San Pedro Springs, San Antonio, Texas. Types: A.M.N.H., 

M.C.Z., Coll. W. S. Creighton. 
Range: low mountains in western Texas and eastern New Mexico. 

The clypeal incision of sancti-hyacinthi is quite different from that 
of any other North American species. In the species where the clypeus 
is incised, the incision is usually broad and shallow. In sancti-hyacinthi 
it is rather narrow and very deep. In some specimens it extends behind 
the tips of the frontal lobes. This species seems to be rather sporadic 
and rare. I have made strenuous efforts to take it in some of the same 
stations where Wheeler secured his specimens but I have never seen 
this insect in the field. 



21. POGONOMYRMEX SUBDENTATUS Mayr 

P. subdentatus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 971 (1870) 9 ; 
Mayr, Ibid., Vol. 37, p. 610 (1887); Wheeler, Amer. Naturalist, Vol. 36, 
p. 94, fig. 6 (1902) 9 ; Wheeler, Psyche, Vol. 9, p. 391 (1902) 9 ; Olsen, 
Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 497, pi. 5, fig. 2 
(1934) 9. 

Type loc: California. Types: none in this country. 

Range: known from California only. 



132 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The area of greatest abundance for subdentatus seems to be the 
region just south of San Francisco, where it occurs in the dry valleys 
of the Coast Range. There are records of subdentatus coming from 
stations as far south as San Diego but it is by no means as abundant 
in the southern part of the state as is subnitidus. 



22. POGONOMYRMEX SUBNITIDUS Emery 

P. occidentalis var. subnitidus Emery, Zool. Jahrb. Syst., Vol. 8, p. 310 (1895) 9 ; 

Wheeler, Amer. Naturalist, Vol. 36, p. 98 (1902); Wheeler, Psyche, Vol. 9, 

p. 391 (1902) 9 . 
P. subnitidus Wheeler, Psyche, Vol. 21, p. 156 (1914); Olsen, Bull. Mus. Comp. 

Zool. Harvard, Vol. 77, No. 8, p. 498, pi. 4, fig. 3 (1934) 9 . 
Type loc: San Diego County, California. Types: none in this country. 
Range: coastal region of southern California north to the Mojave Desert. 



Subgenus EPHEBOMYRMEX Wheeler 

23. POGONOMYRMEX (EPHEBOMYHMEX) IMBERBICULUS Wheeler 

P. imberbiculus Wheeler, Amer. Naturalist, Vol. 36, p. 86, fig. 1, 2 (1902) 9 . 

P. (Ephebomyrmex) imberbiculus Wheeler, Psyche, Vol. 9, p. 390 (1902) 9 ; 
Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 495, pi. 6, fig. 3 
(1934) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 544, 
pi. 5, fig. 21 (1947) 9 . 

Type loc: Mt. Barker, Austin, Texas. Types: A.M.N.H., M.C.Z. 

Range: western Texas and southern New Mexico. 

This species is our only representative of the subgenus Ephebomyrmex 
which is at all abundant. It appears to be fairly widespread in western 
Texas, where it occurs on upland plateaus. The colonies are com- 
paratively small and the rather obscure nests are often built under 
stones. 



24. POGONOMYRMEX (EPHEBOMYRMEX) IMBERBICULUS 
TOWNSENDI Wheeler 

P. (E.) townsendi Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 80 (1909) 9 ; 

Olsen, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 495, pi. 8, 

fig. 2 (1934) 9 . 

Type loc: Ojo del Cerro Chilicote, Chihuahua, Mexico. Type: M.C.Z. 
Range: deserts of southern Arizona south into Mexico. 



CREIGHTON: ANTS OF NOKTH AMERICA 166 

Although both Wheeler and Olsen treated townsendi as a separate 
species, I believe that it should be considered as a southern race of 
imberbiculus. It is very rare within our borders and the few specimens 
which have been taken have come from stations close to the Mexican 
boundary. The main range of this subspecies undoubtedly lies in 
Mexico. 

25. POGONOMYEMEX (EpHEBOMYRMEx) PiMA Wheeler 

P. (E.) pima Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 79 (1909) 9 ; Olsen, 
Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 8, p. 495, pi. 7, fig. 1 (1934) 9 . 
Type loc: Tucson and Phoenix, Arizona. Types: M.C.Z., A.M.N.H. 
Range: desert areas in central and southern Arizona. 



Genus STENAMMA Westwood 
(Plate 17, figures 1-4) 

The taxonomic difficulties which surround the North American 
representatives of Stenamma are out of all proportion to the small 
number of forms involved. There are at present nine described forms 
which occur in the United States and Canada. Although Emery, Forel 
and Wheeler have each made revisionary proposals for this group, 
the existing arrangement is far from satisfactory. In order that the 
treatment followed in the present work may be fully understood, I 
have prefaced it with an account of the previous revisionary proposals. 
Unless these are considered, it is unlikely that an accurate idea of the 
relationships within the group can be secured. 

When Mayr first described nearcticum and brevicorne in 1886, the 
only other known species was the European westwoodi. Mayr was able 
to show that the wing venation of nearcticum is identical with that of 
westwoodi, i.e., the inner branch of the cubital vein arises from the 
cross- vein. The venation of brevicorne differed in that the inner branch 
of the cubital vein arises from the middle of the cubital cell. Mayr 
had associated workers with his winged specimens of nearcticum but, 
in the following year, he restricted the description to the sexual castes. 
Although more than a half century has passed, and although much 
study has been devoted to the matter, the worker of nearcticum still 
remains unknown. This has been one of the major stumbling blocks 
in the taxonomy of our forms. When Emery dealt with the North 
American representatives of Stenamma in 1895, he used the venational 
similarity of nearcticum and westwoodi to make nearcticum a subspecies 
of the latter insect. In addition he recognized the subspecies diecki 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



and the variety impressum, both of which he assigned to westwoodi. 
This still left brevicorne recognizable only because of its wing venation. 

In 1901 Forel took a hand in the matter. I wish to examine his 
conclusions with some care for it seems to me that most of the ills 
which beset our representatives of Stenamma can be attributed directly 
to them. I have, therefore, presented below Wheeler's translation of 
Forel's statement. 

'This subgenus (Stenamma) presents an almost inextricable tangle 
of allied forms. The sculpture of the American species is denser than 
that of S. westwoodi of Europe. I believe that they should be separated 
specifically if only for the sake of unravelling the tangle. On the other 
hand I doubt whether S. diecki Emery, really belongs to nearcticum 
and believe that it belongs rather to brevicorne. Emery gives the 
differential characters between the American workers and the typical 
westwoodi but not between the workers of nearcticum and brevicorne. 
Now the fundamental difference between these two species lies in the 
wings, and none of the specimens described by Emery as nearcticum, 
diecki, etc., seem to have possessed these appendages, as the author 
makes no mention of them. It seems to me more prudent, therefore, 
since the winged sexes are so little known, to retain the name ne- 
arcticum only for the female and male described by Mayr and to 
consider all other American forms as races or varieties of brevicorne 
until we have proof to the contrary.' 

There can be no doubt as to what contrary proof Forel had in mind. 
If the winged castes of diecki, impressum and impar should have proven 
to have the venation of nearcticum, Forel would have been wrong in 
assigning these insects to brevicorne. But the fallacy which neither 
Forel nor Wheeler appreciated is the assumption that if these insects 
have a wing venation like that of brevicorne they must be considered 
infraspecific variants of that species as a result. There is no logical 
basis for such a belief, yet it has formed the cornerstone on which our 
treatment of these forms has rested. This has been due in large part 
to Wheeler's 1903 revision of this group. W r heeler not only accepted 
Forel's stand without reservation but gave it additional prominence by 
stating that he had been able 'to establish the. truth of Professor 
Forel's conjecture.' Wheeler had received a cotype of diecki from 
Emery and one of impar from Forel. With these he was able to make 
the necessary association with the winged castes which showed that 
diecki and, presumably impar also, had the wing venation of brevicorne. 
As a result Wheeler treated these forms, and others which he subse- 
quently described, as variants of brevicorne. The only North American 
representatives of Stenamma which have managed to escape the all- 
embracing clutch of brevicorne are nearcticum and the insect which 
M. R. Smith described in 1930 as fovolocephalum. 



CREIGHTON: ANTS OF NORTH AMERICA 



It should be patent to anyone who has worked out the distribution 
of the various forms which have been assigned to brevicorne that the 
arrangement cannot possibly be defended on a distributional basis. 
The group shows a welter of coincidental ranges that would discourage 
any attempt to treat most of the variants as geographical races. In 
the northeastern United States there are three forms, schmitti, im- 
pressum and impar, which often occur in the same stations and whose 
nests are not infrequently in close proximity. The little known variants 
heathi and sequoiarum occur on the west coast, hence their ranges are 
widely separated from those of the three eastern forms just mentioned. 
But the range of diecki includes both the eastern and western forms, 
and in addition the situation is complicated by the occurrence of the 
typical brevicorne, whose range covers the northeastern United States 
and extends as far west as Wisconsin. Despite these overlapping 
ranges the variants manage to maintain their distinctive characteristics 
rather well, a circumstance that would be unthinkable if they were 
geographical races. They are behaving as species, not as subspecies, 
and if any satisfactory treatment for the group is to be made, this fact 
will have to be recognized. Of this group of forms only sequoiarum 
can, in my opinion, be considered as a geographical race. The rest 
must be treated as species and in most cases their structural dis- 
tinations are good enough to justify this view. That this fact has not 
been recognized sooner is undoubtedly attributable to the undue in- 
fluence which Forel's views have exerted on the taxonomy of this 
group. 

The habits of our species are little known. They form small colonies 
of a few dozen workers. The nests are usually situated in wooded 
areas and may be built in leaf mould, under stones or logs or beneath 
thick, loose moss. The ants are timid, sluggish and rarely seen outside 
the nest. Because of this fact it was Wheeler's opinion (1903) that 
they are subterranean or nocturnal in habit. Wheeler also believed 
that they feed on small larvae and other animal food. There is, how- 
ever, no published data to indicate the correctness of these surmises. 
The insects seem to offer considerable possibilities for those interested 
in habit studies. 

The following key is an expansion and modification of that published 
by Wheeler in 1903: 

Key to the species of Stenamma 

1 . Inner branch of the cubital vein arising from a cross-vein (worker unknown) 

nearcticum 

Inner branch of the cubital vein arising from the middle of the cubital cell 
(the remainder of the key deals with the worker caste) 2 



136 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

2. Dorsum of the thorax, petiole and postpetiole with irregular, rugose, 

reticulate sculpture 3 

Dorsum of the thorax, petiole and postpetiole showing at least some 
longitudinal rugae near the middle, those at the sides curved but scarcely 
reticulate 4 

3. Eyes with 6-7 facets in greatest diameter fovolocephalum 

Eyes with no more than four facets in greatest diameter heathi 

4. Entire head, thorax and nodes of the petiole opaque, the interrugal spaces 

roughened and dull 5 

Rear of head, thorax and nodes of the petiole feebly to strongly shining, 
the interrugal spaces smooth 7 

5. Length, 2.5-4 mm.; color dark brown to black brevicorne 

Length 2.4-3 mm. ; color brown or red 6 

6. Eyes with at least six facets in greatest diameter; epinotal spines well 

developed impar 

Eyes with only three or four facets in greatest diameter; epiribtal spines 
small schmitti 

7. Mesoepinotal depression moderate; epinotal spines robust and only slightly 

directed upward; color reddish brown 8 

Mesoepinotal depression broad and deep; epinotal spines short and dis- 
tinctly directed upward; color dark brown impression 

8. Rugae at the base of the gaster rather feeble and indistinct diecki 

Rugae at the base of the gaster pronounced and prominent 

diecki subsp. sequoiarum 

1. STENAMMA BEEVICORNE (Mayr) 

Aphaenogaster brevicorne Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 447 

(1886) 99. 
5. brevicorne Emery, Zool. Jahrb. Syst., Vol. 8, p. 298 (1895) 9 9 d" ; Porel, 

Ann. Soc. Ent. Belg., Vol. 45, p. 347 (1901); Wheeler, Psyche, Vol. 10, 

p. 166 (1903) 9 . 
S. nearcticum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 454 (1886) 9 

(not 9 or c7); Mayr, Ibidem, Vol. 37, p. 628 (1887). 
Type loc: Virginia. Types: none in this country. 
Range: northeastern United States and southern Ontario south to Virginia 

and west to Wisconsin. The record from Friday Harbor, Washington 

reported by Wheeler in 1903 appears to have been an error. It may be 

doubted that brevicorne occurs in the far west. 



2. STENAMMA DIECKI Emery 

S. westwoodi subsp. diecki Emery, Zool. Jahrb. Syst., Vol. 8, p. 300 (1895) 9 9 . 
S. brevicorne subsp. diecki Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 347 (1901); 

Wheeler, Psyche, Vol. 10, p. 167 (1903) 9 . 
Type loc: Yale, British Columbia. Types: M.C.Z. 
Range: northeastern United States, southern Canada west to the Pacific coast. 



CREIGHTON: ANTS OF NORTH AMERICA io i 

3. STENAMMA DIECKI subsp. SEQUOIARUM Wheeler 

S. brevicorne subsp. sequoiarum Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 52, p. 520 (1917). 

Type loc: Muir Woods, Mt. Tamalpais, California. Types: M.C.Z., A.M.N.H. 
Range: known from type material only. 

This form is so little known that it is impossible to be certain of its 
exact status. There would seem to be no reason, however, why it 
should not be provisionally regarded as a subspecies of diecki. 

4. STENAMMA FOVOLOCEPHALUM M. R. Smith 

S.fovolocephalum M. R. Smith, Ann. Ent. Soc. Amer., Vol. 23, p. 564 (1930) 9 . 
S. foveolocephalum M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 554, 

pi. 6, fig. 22 (1947) 9 . 
Type loc: Ackerman, Mississippi. Types: Coll. M. R. Smith; Coll. Dept. 

Ent. A & M Coll. Miss. 
Range: known only from type material. 

5. STENAMMA HEATHI Wheeler 

S. brevicorne subsp. heathi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 410 (1915) 9 . 

Type loc: Kings River Canyon, California. Types: M.C.Z., A.M.N.H. 
Range: known only from type material. 

6. STENAMMA IMPAR Forel 

S. brevicorne subsp. impar Forel, Ann.Soc.Ent.Belg., Vol. 45, p. 347 (1901) 9 5 . 
Type loc: worker, Potomac River, Virginia: female, Franklin Park, Boston, 

Mass. Types: A.M.N.H. 
Range: Atlantic Coast States, Massachusetts to Virginia. 

The single specimen marked as a type in the collection of the 
A.M.N.H. bears the locality label 'Washington, D. C.' It may or 
may not be a part of the type series but in any case it was collected 
and identified by Forel. 



STENAMMA IMPRESSDM Emery 



S. westwoodi subsp. diecki var. impressum Emery, Zool. Jahrb. Syst., Vol. 8, 

p. 301 (1895) 9 9 . 
S. brevicorne subsp. diecki var. impressum Forel, Ann. Soc. Ent. Belg., Vol. 45, 

p. 347 (1901); Wheeler, Psyche, Vol. 10, p. 167 (1903) 9 . 



ld BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: Richs Spring, New York. Types: none in this country. 

Range: southern New York south down the Appalachian Highlands to 

Tennessee. Cole reports that in the southern part of the range the insect 

occurs only at elevations above 5000 feet. 



8. STENAMMA NEAKCTICUM Mayr 

S. neoarcticum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 454 (1886) 9 cT 
(not 9); Mayr, Ibidem, Vol. 37, p. 628 (1887); Forel, Ann. Soc. Ent. 
Belg., Vol. 45, p. 347 (1901); Wheeler, Psyche, Vol. 10, p. 166 (1903). 
S. westwoodi subsp. nearcticum Emery, Zool. Jahrb. Syst., Vol. 8, p. 299 
(1895) 9. 

Type loc: California (by present restriction). Types: none in this country. 

Range: Pacific Coast States and British Columbia. 

It would seem necessary to restrict the type locality of nearcticum 
to California, since the insect does not occur in the eastern states. It 
may be that Mayr's specimens from Virginia and New Hampshire 
were those which he subsequently discarded as not belonging to 
nearcticum. 

9. STENAMMA SCHMITTI Wheeler 

S. brevicorne subsp. schmitti Wheeler, Psyche, Vol. 10, p. 167 (1903) 9 . 
Type loc: St. Vincent, Pennsylvania. Types: A.M.N.H., M.C.Z. 
Range: at present recorded only from Pennsylvania and Ohio. The insect 
probably occurs in several of the central Atlantic States as well. 



Genus APHAENOGASTER Mayr 



Subgenus ATTOMYRMA Emery 
(Plate 18, figures 1-4) 

Under the plan which Emery proposed in the Genera Insectorum, 
all representatives of Aphaenogaster coming from America north of 
Mexico were placed in the subgenus Attomyrma. Although this plan 
has been followed in the present volume, it should be understood that 
Emery's arrangement is by no means conclusive. The definitive 
criterion which distinguishes Attomyrma from the subgenus Dero- 
myrma is a difference in wing venation. The other criteria which 
Emery used are less satisfactory. It is not practical to attempt to 
separate the two subgenera by using the shape of the head in the 



CREIGHTOX: ANTS OF NORTH AMERICA idy 

worker caste. A number of our species, which Emery included in 
Attomyrma, have workers in which the head is produced into a 'neck' 
in all respects similar to that which is supposed to distinguish the 
worker of Deromyrma. Several of these long-headed species are known 
only from the worker caste. Until the sexual phases can be associated 
with such workers, it is impossible to be certain whether they belong 
to Attomyrma or to Deromyrma. A similar consideration applies to 
some of the species which Emery assigned to Deromyrma. A final 
solution of this difficulty will depend upon a much better knowledge 
of the sexual phases than we possess at present. In the meantime it 
seems preferable to employ Emery's arrangement. 

The nesting habits of our species of Aphaenogaster vary widely. 
The majority of the species nest in the soil and usually start the nest 
beneath some covering object. If this happens to be a log, the ants 
may construct a part of the nest in it but the main part of the nest 
is usually subterranean. The nests of lamellidens and tennesseensis , on 
the other hand, are usually constructed in rotten stumps and fallen 
logs with few of the passages running into the soil. This preference for 
nests in rotting wood takes a rather unusual turn in the case of mariae. 
The writer has never been able to find mariae in the field but Dr. 
L. G. Wesson, who has taken it on several occasions, tells me that the 
insect always nests in dead branches at a considerable height above 
the ground. To judge from the rather scanty data at present available 
miamiana is also arboreal. I have received specimens of this insect 
taken from hollow pecan twigs. . 

The nest-founding activities of two of our species of Aphaenogaster 
are in need of investigation. It has been generally assumed that 
mariae and tennesseensis are temporary social parasites on fulva or 
rudis. The first two species both possess small females and that of 
tennesseensis is further distinguished by its very smooth and shining 
surface. This characteristic is all the more striking because the worker 
of tennesseensis has a rough and heavy surface sculpture. It seems 
entirely probable that the structural peculiarities shown by the female 
of tennesseensis are connected with a parasitic type of nest founding 
but nothing definite is known in this regard. Indirect evidence is 
offered by the fact that a few mixed colonies of tennesseensis and fulva 
have been reported. 

Our species of Aphaenogaster are by no means uniform in their 
degree of differentiation. This has led to confusion in the case of 
closely related species, several of which have been regarded as sub- 
species. Further confusion has resulted from the incorrect assumption 
that certain species are strictly monomorphic. Varietal names have 
been proposed for the smaller workers and even for minims from 



14U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

incipient nests. It should be obvious that size distinctions of this sort 
are of no significance unless accompanied by comparable differences in 
the sexual castes. Finally, a number of our species are prone to 
considerable variation in color. By selecting certain nest series it is 
possible to secure color varieties which are strikingly distinct. Yet it 
is only rarely that such color differences have a geographical signifi- 
cance and when they do, the color is usually correlated with a structural 
difference. The above considerations have led me to treat many of the 
described variants with a heavy hand. Although a large number of 
varieties have gone into the synonymy, there is consolation in the fact 
that those which remain can be handled without splitting nest series 
or violating zoogeographical precepts. 



Key to the species of Attomyrma 

1. Antennal scape with a conspicuous lobe which extends rearward along the 

basal fourth or fifth of the scape 2 

Antennal scape without a basal lobe or, if a small lobe is present, it 
projects forward and does not involve the basal fifth of the scape 4 

2. Lobe of the scape, seen from the side, flat and thin, its length usually not 

more than one-fifth the length of the scape ashmeadi 

Lobe of the scape, seen from the side, thick, its upper face forming an 
obtusely projecting angle in the middle, its length usually one-fourth the 
length of the scape or longer 3 

3. Head (mandibles excluded) one-fourth longer than broad, the sides not 
narrowed immediately behind the eyes, the occiput broadly and evenly 
rounded; longitudinal rugae usually extending onto the occiput. . .treatae 
Head (mandibles excluded) one-third longer than broad, the sides be- 
ginning to narrow immediately behind the eyes, the occiput narrow and 
flat in the middle; posterior third of the head granulose but only rarely 
with longitudinal rugae treatae subsp. pluteicornis 

4. Basal quarter of the first gastric segment with delicate striae which spread 

fan-wise from the attachment of the postpetiole mariae 

Gaster without basal striae, or if striae are present they do not spread 
fan-wise and are limited to the basal eighth of the segment 5 

5. Outer face of the frontal lobe bearing a flange which projects rearward in 

the form of a tooth lamellidens 

Outer face of the frontal lobe without a toothed flange 6 

6. Postpetiole broader than long and suboval in shape; epinotal spines longer 

than the basal face of the epinotum tennesseensis 

Postpetiole as long as broad or longer than broad, globular or like a 
truncated cone in shape; epinotal spines, when present, shorter than the 
basal face of the epinotum 7 

7. Antennal scapes of the larger workers (not always true of the minims) 
surpassing the occipital margin by an amount less than the. length of the 



CKEIGHTON: ANTS OF NORTH AMERICA 



first two funicular joints 8 

Antennal scapes of all workers surpassing the occipital margin by an 
amount greater than the length of the first two funicular joints 12 

8. Mesopleurae heavily sculptured and opaque 10 

Mesopleurae at least in part smooth and shining 9 

9. Cephalic rugae delicate but clearly visible; color piceous brown. . patruelis 
Cephalic rugae very feeble, often hard to see without oblique illumination; 
color yellow patruelis subsp. bakeri 

10. Head with abundant, fine, punctato-rugose sculpture between the longi- 
tudinal rugae; color castaneous brown to piceous brown 11 

Head with very feeble interrugal sculpture; head and thorax orange 
yellow, gaster deep brown uinta 

11. Largest workers 6 mm. in length, female 8 mm. in length; color usually 

castaneous brown subterranea subsp. valida 

Largest workers 4.5 mm. in length, female 6.5 mm. in length; color usually 
piceous brown subterranea subsp. occidenlalis 

12. Epinotum unarmed, rounded or angular but without distinct teeth or 

spines 13 

Epinotum armed with distinct teeth or spines 15 

13. Clypeus distinctly carinate; head widest at the level of the eyes and about 

equally narrowed behind and in front of them mutica 

Clypeal carina indistinct; the head much more narrowed behind the eyes 
than in front of them 14 

14. Base of the antennal scape with a small lobe which projects anteriorly; 
node of the petiole longitudinally oval when seen from above and scarcely 

wider than its posterior peduncle floridana 

Base of the antennal scape without a lobe; node of the petiole almost 
circular when seen from above and distinctly wider than its posterior 
peduncle boulderensis 

15. Middle of the pronotum with very feeble sculpture, its surface strongly 

shining; epinotal spines very slender flemingi 

Entire pronotum heavily shagreened or densely sculptured, its surface 
opaque or subopaque; epinotal spines not notably slender 16 

16. Base of the antennal scape with a small, angular lobe which projects 

forward 17 

Base of the antennal scape without such a lobe 18 

17. Epinotal spines only a little shorter than the basal face of the epinotum 

macrosjrina 
Epinotum armed with short, triangular teeth huachucana 

18. Anterior edge of the mesonotum rising abruptly above the adjacent portion 
of the pronotum, the transverse welt thus formed distinctly concave in 
the middle; epinotal spines at least as long as the declivious face of the 

epinotum and strongly directed upwards fulva 

Mesonotum not abruptly elevated above the pronotum or, if it is higher, 
the anterior edge does not form a transverse welt; epinotal spines rarely 
as long as the declivious face of the epinotum and usually directed back- 
ward 19 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



19. Head of the largest workers (mandibles excluded) not more than one-sixth 
longer than broad; head of the smaller workers approximately one-fifth 

longer than broad 21 

Head of the worker, regardless of size, approximately one-third longer 
than broad 20 

20. Large workers 5.5 mm. in length; female 7 mm. in length texana 

Large workers 4.5 mm. in length; female 5.5 mm. in length 

texana subsp. carolinensis 

21. Eyes with 13-15 facets in greatest diameter; epinotal spines slightly 
incurved when seen from above; basal face of the epinotum with very 

coarse, transverse rugules miamiana 

Eyes with 10-11 facets in greatest diameter; epinotal spines divergent 
when seen from above; transverse rugae on the basal face of the epinotum 
feeble "and often replaced by punctures 22 

22. The area between the eye and the frontal lobe with reticulate rugae which 
are not obscured by the interrugal sculpture; pronotum often crossed with 

transverse rugules rudis 

The area between the eye and the frontal lobe densely punctate with the 
punctures largely obscuring or replacing the rugae; pronotum evenly 
punctato-granulose, without transverse rugules rudis subsp. picea 



1. APHAENOGASTER (ATTOMYRMA) ASHMEADI Emery 

A. treatae var. Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 444 (1886) 9 . 
A. treatae subsp. ashmeadi Emery, Zool. Jahrb. Syst., Vol. 8, p. 302 (1895) 9 . 
A. (Attomyrma) treatae subsp. harnedi Wheeler, Psyche, Vol. 26, p. 50 (1919) 9 . 
Type loc: Florida. Types: none in this country. 
Range: eastern Gulf Coast states. 

The only difference which separates harnedi from ashmeadi is the 
lighter color of the former insect. Structurally the two are identical. 
The distinction which Wheeler attempted to make in the case of gastric 
punctuation will not hold. In any substantial series of workers from 
a single nest both sorts of punctuation are present. Wheeler appears 
to have been misled on this point because he lacked adequate material 
of ashmeadi at the time when harnedi was described. 



2. APHAENOGASTER (ATTOMYRMA) BOULDEHENSIS M. R. Smith 

A. (Attomyrma) boulderensis M. R. Smith, Great Basin Naturalist, Vol. 2, 

No. 3, p. 120 (1941) 9 . 

Type loc: Horseshoe Island, Mead Lake, Boulder Dam, Arizona. 
Type: U.S.N.M. Paratypes: U.S.N.M., Coll. V. M. Tanner, Coll. W. S. 

Creighton. 
Range: known only from type material? 



CREIGHTON: ANTS OF NORTH AMERICA 143 

There appears to have been considerable confusion in regard to 
boulderensis prior to its recognition as a separate species by Dr. Smith 
in 1941. Both Wheeler and I had confused boulderensis with Pergande's 
mutica, a species from which it is clearly distinct. Through the 
courtesy of Dr. M. R. Smith I have recently been able to examine the 
types of both boulderensis and mutica. This examination settled one 
question but raised another. I now feel considerable doubt that mutica 
occurs in the United States and believe that previous records attributed 
to that species probably should go to boulderensis. Because of the 
uncertainty in regard to these records I have made no attempt to 
determine the range of boulderensis but it will not be surprising if 
subsequent investigation shows the insect occurring as far east as 
trans-Pecos Texas. 

3. APHAENOGASTER (ATTOMYRMA) FLEMINGI M. R. Smith 

A. texana subsp. flemingi M. R. Smith, Ent. News, Vol. 39, p. 275 (1928) 9 . 
Type loc: A & M College, Mississippi. Types: Coll. M. R. Smith, M.C.Z., 

Coll. Dept. Ent. Miss. A & M College, Coll. W. S. Creighton. 
Range: known only from type material. 

The slender epinotal spines and feeble thoracic sculpture of flemingi 
readily distinguish this insect from texana. It must be considered as 
a separate species for texana occurs so widely in the southeastern 
United States that there is no possibility that flemingi can have a 
range separate from that of texana. 

4. APHAENOGASTER (ATTOMYRMA) FLORIDANA M. R. Smith 

A. (Attomyrma) floridana M. R. Smith, Great Basin Naturalist, Vol. 2, No. 3, 

p. 118 (1941) 9 . 

Type loc: Gretna, Florida. Type and Para types: U.S.N.M. 
Range: known from Florida only. 

A. floridana appears to be rather closely related to huachucana for 
both species have elongate heads and in each the scape bears a small 
angular lobe at the base. The two species are, however, quite clearly 
distinct. The size of floridana is notably smaller (4.5-5 mm.), it is 
much more lightly sculptured and the epinotum is, at most, angular 
and lacks the distinct teeth which are present in huachucana. 



5. APHAENOGASTER (ATTOMYRMA) FULVA Roger 

A. fulva Roger, Berl. Ent. Zeitschr., Vol. 7, p. 190 (1863) 9 ; Mayr, Verh. 
Zool-bot. Ges. Wien, Vol. 36, p. 445 (1886) 9 9 cf . 



144 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Stenamma fulvum Emery, Zool. Jahrb. Syst., Vol. 8, p. 303 (1895) 9 9 <?. 
A.fulva var. ruWda Enzmann, Jour. N. Y. Ent. Soc., Vol. 55, pi. 8 (1947) 9 . 
Type loo: 'North America'. Types: none in this country. 
Range: northeastern United States to northern Alabama and west to Ohio. 

In the present work a number of forms, previously regarded as 
varieties of fulva, have been treated as representatives of a separate 
species, rudis. For a discussion of this matter see the introduction to 
rudis. 

6. APHAENOGASTER (ATTOMYRMA) HUACHUCANA Creighton 

A. (Attomyrma) huachucana Creighton, Psyche, Vol. 41, p. 189 (1934) 9 . 

Type loc: Ramsey Canyon, Huachuca Mts. (7000') Arizona. 

Cotypes: Coll. W. S. Creighton, M.C.Z., A.M.N.H., U.S.N.M., Coll. A. C. 

Cole. 
Range : known only from type material. 



7. APHAENOGASTER (ATTOMYHMA) LAMELLIDENS Mayr 

A. lamellidens Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 444 (1886) V 9 d" . 

flienamma lamellidens Emery, Zool. Jahrb. Syst., Vol. 8, p. 302 (1895). 

A. (Attomyrma) lamellidens var. nigripes M. R. Smith, Ent. News, Vol. 34, 
p. 308 (1923) 9 . 

Type loc: Virginia (by present restriction). Types: none in this country. 

Range: areas of low or moderate elevation throughout the entire southeastern 
United States from southern Delaware to Florida and west to the Missis- 
sippi Valley. 

I have recently discussed with Dr. Smith the circumstances under 
which the variety nigripes was described and have presented them 
here because of their instructive character. When Dr. Smith first 
encountered the specimens which were later to be called nigripes, he 
sent some of them to Dr. Wheeler for specific identification. In reply 
Dr. Wheeler stated that he regarded the insect as a new variety of 
lamellidens which differed from the typical form because of its black 
legs. In 1923 lamellidens was represented in Dr. Wheeler's collection 
by a few old and badly faded specimens whose color had lost all re- 
semblance to the lively color of fresh material. These specimens, highly 
atypical as far as color is concerned, became the 'typical lamellidens' 
to which nigripes was contrasted. This difficulty would probably 
never have arisen if Wheeler had possessed a field acquaintance with 
lamellidens. The writer has taken lamellidens in a large number of 
stations extending from southern Delaware to the Gulf of Mexico. I 
have never seen a colony in the field which did not have the charac- 



CREIGHTON: ANTS OF NORTH AMERICA 145 

teristics of nigripes. I have never seen any fresh specimens which 
showed the color that Wheeler considered characteristic of his 'typical 
lamellidens' '. For these reasons I propose to regard nigripes as identical 
with lamellidens and to treat Wheeler's color distinction as a matter 
of no taxonomic significance. 

8. APHAENOGASTER (ATTOMTHMA) MACROSPINA M. R. Smith 

A. texana subsp. macrospina M. R. Smith, Ann. Ent. Soc. Amer., Vol. 27, 

No. 3, p. 386, figs. 1, 2 (1934) 9 . . 

Type loe: Charleston, South Carolina. Types: Coll. M. R. Smith, U.S.N.M. 
Range: South Carolina to Florida. 

In my opinion macrospina should be regarded as a separate species 
rather than as a subspecies of texana. From a geographical standpoint 
the range of macrospina is largely blanketed by that of texana, which 
removes the possibility of treating macrospina as a geographical race. 
There is little difficulty in according specific status to macrospina for 
the insect shows a number of structural differences which separate it 
from texana. In macrospina the eyes occur closer to the middle of the 
side of the head (a little in front of the middle in texana). The posterior 
half of the head in macrospina is less narrowed than that of texana, 
with the occipital margin distinctly wider and the occipital angles 
more broadly rounded. The scape of macrospina has a small, basal, 
angular lobe which is lacking in texana. The epinotal spines of ma- 
crospina are far longer and heavier than those of texana. The sculpture 
of macrospina is less heavy than that of texana, particularly on the 
posterior part of the head and the pronotum, which are smooth and 
shining in macrospina. 

9. APHAENOGASTER (ATTOMYRMA) MARIAE Forel 

A. marine Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 41 (1886) 9 ; Mayr, 
Verh. Zool-bot. Gcs. Wien, Vol. 36, p. 443 (1886) 9 . 

Stenamma marine Emery, Zool. Jahrb. Syst., Vol. 8, p. 301 (1895). 

Type loc: Florida. Types: none in this country. 

Range: apparently very discontinuous; scattered records from Florida, Missis- 
sippi, Ohio and Illinois. 



10. APHAENOGASTER (ATTOMYRMA) MIAMIANA Wheeler 

A. (Attomyrma) texana var. miamiana Wheeler, Jour. N. Y. Ent. Soc., Vol. 40, 

p. 5 (1932) 9 9 rf 1 . 

Type loc: Miami, Florida. Types: M.C.Z., A.M.N.H. 
Range: Florida, southern Alabama and Mississippi. 



140 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The color of miamiana varies considerably. Its large eyes, heavy 
sculpture and incurved epinotal spines permit an easy separation from 
rudis, to which it seems rather closely related. This species was im- 
ported into the New York area at some period prior to 1908 but has, 
apparently, died out since. 



11. APHAENOGASTER (ATTOMYRMA) MUTICA Pergande 

A. mutica Pergande, Proc. Calif. Acad. Sci. (2), Vol. 5, p. 891 (1895) 9 . 
Type loe: San Jose del Cabo, Mexico. Types: U.S.N.M. 
Range: Lower California. 

Wheeler has recorded mutica from the Brownsville region of Texas 
but there is reason to doubt that mutica occurs within our borders 
(see discussion under boulder ensis) . If so, one would expect to find it 
along the southern border of California rather than in Texas. This 
species appears to be rather closely related to patruelis and, when we 
have a better knowledge of the ant fauna of Lower California, it may 
prove to be a southern race of patruelis. 



12. APHAENOGASTER (ATTOMYRMA) PATRUELIS Forel 

A. patruelis Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 41 (1886) 9 ; Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 270 (1904). 
Stenamma subterranea subsp. patruelis Emery, Zool. Jahrb. Syst., Vol. 8, 

p. 302 (1895). 
A. (Attomyrma) patruelis subsp. willowsi Wheeler, Proc. Calif. Acad. Sci., 

Vol. 21, No. 6, p. 64 (1933) 9 . 

Typeloc: Guadeloupe Island, Lower California. Types: none in this country. 
Range: (in the United States) coastal islands of California. 



In my opinion there is no doubt that the subspecies willowsi, which 
Wheeler described from a single worker specimen, is a synonym of 
patruelis. According to Wheeler, willowsi 'differs from the typical 
patruelis only in the less convex base of the epinotum, less developed 
sculpture and paler coloration.' Through the kindness of Dr. Cockerell 
the writer has had for study an excellent series of specimens from St. 
Nicholas Island, the type locality of willowsi. The variation within 
the series is such that it would include both the typical patruelis and 
willowsi. For this reason willowsi has been treated as a synonym of 
patruelis. 



CREIGHTON: ANTS OF NORTH AMERICA 14 

13. APHAENOGASTER (ATTOMYRMA) PATRUELIS BAKERI Wheeler 

A. patruelis subsp. bakeri Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, 

p. 270 (1904) 9 . 
Type loo: Catalina Island, California. Types: A.M.N.H., M.C.Z., Coll. 

W. S. Creighton. 
Range : known only from type material. 



14. APHAENOGASTER (ATTOMYRMA) RUDIS Emery 

In the present work rudis and its subspecies picea have been sepa- 
rated from fulva and treated as representatives of a separate species. 
This treatment is necessary for two reasons. In the first place, there 
is a marked and constant difference in the thoracic structure of the 
two species which involves not only the length of the epinotal spines 
but also the over all proportions of the thorax, especially the meso- 
notum (see key). Added to this is the fact that, since fulva occurs in 
the same stations as rudis or picea, the last two forms cannot properly 
be regarded as subspecies of fulva. In addition to the change proposed 
above I have abandoned Buckley's name aquia, since it seems im- 
possible to determine to what form it applies. Since all of these 
proposals run counter to the arrangement which has been accepted 
for the last half a century, I wish to review certain difficulties which 
have beset this group of forms from the start. 

Three years after Roger presented the original description of fulva 
Buckley described an insect which he called Myrmica aquia. The 
description is so poor that it offers no clue even as to the genus. That 
anyone could have ascertained the species from the description alone 
is unthinkable. It may be assumed, therefore, that when Mayr made 
aquia a synonym of fulva in 1886, he did so on the basis of specimens 
sent him by Norton. It is much to be regretted that aquia could not 
have been allowed to remain as a synonym of fulva. In 1895, however, 
Emery began working with the rather heterogeneous assemblage of 
material that had accumulated under fulva and proposed to draw 
taxonomic distinctions based in large part on the length of the epinotal 
spines. Emery recognized that Roger's fulva is distinguished by long 
epinotal spines, hence he felt justified in giving subspecific status to 
those variants with short epinotal spines. This made it necessary to 
resuscitate Buckley's aquia, for the description of aquia states that 
the epinotal spines are small. Since Emery recognized more than one 
short-spined variant, it became necessary for him to select one of these 
as representing Buckley's aquia. This choice appears to have been 
purely arbitrary and a matter about which Emery was none too happy, 



148 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

for he stated that Pergande agreed with him that aquia should be 
assigned to fulva, a curious point to raise in the case of a form which 
had existed as a synonym of fulva for the previous nine years. There 
is, however, one important consideration to be borne in mind. In 1895 
Emery presented simultaneously the descriptions of aquia, rudis and 
picea. It is clear, therefore, that he felt that he was dealing with three 
distinct forms. Subsequent workers have found little difficulty in 
distinguishing between aquia and picea but rudis has remained some- 
thing of an enigma. The reason for this became clear to the writer 
after examining specimens identified as rudis by Emery. Emery's 
rudis is the insect to which Wheeler and most of the workers on this 
side of the Atlantic have given the name aquia. This insect is slightly 
larger, lighter in color and more heavily sculptured than picea. If this 
is the case, what then is Emery's redescribed aquia? I believe that 
Emery's aquia is an intergrade between rudis and picea. In the eastern 
United States the range of rudis is separated from that of picea by an 
elevational difference, the latter form occurring at higher altitudes 
through the Appalachian Highlands, while rudis occurs in the piedmont 
areas at their base. There is thus the opportunity for intergradation 
over a rather extensive area and intergrades may be found from 
southern New England to North Carolina. This fact was clearly 
apparent to Emery, who, at the end of his redescription of aquia, 
commented on the intergrading character of this form. With the 
above facts in mind, it seems to the writer that it is time to stop 
fumbling with aquia and rid the nomenclature of this chronic ill. We 
do not know what Buckley's aquia was. Emery's aquia appears to 
have been an intergrade which should never have been named. I 
propose, therefore, to place aquia in the list of unrecognizable forms. 
There follows the synonymy of A. (Attomyrma) rudis Emery: 

A. fulva var. rudis Emery, Zool. Jahrb. Syst., Vol. 8, p. 305 (1895) 9 9 d" . 
Type loc: Virginia (by present restriction). Types: none in this country. 
Range: southern New England west to Wyoming and south through the 
piedmont to Alabama. 



15. APHAENOGASTER (ATTOMYRMA) RUDIS PICEA Emery 

A. fulva var. picea Emery, Zool. Jahrb. Syst., Vol. 8, p. 305 (1895) 9 9 cf. 
Type loc: Connecticut (by present restriction). Types: none in this country. 
Range: Nova Scotia south through New England and down the Appalachian 
Highlands to North Carolina. 



CREIGHTON: ANTS OF NORTH AMERICA 



16. APHAENOGASTER (ATTOMYRMA) SUBTEHRANEA 
OCCIDENTALIS Emery 

There are several questions connected with the New World forms of 
subterranea which are in need of clarification. The first of these 
concerns the status of the subspecies to which Emery gave the name 
occidentalis. Emery was of the opinion that this subspecies is very 
closely related to subterranea but he cited slight differences (longer 
head, slenderer scapes, etc.) which he felt entitled occidentalis to 
subspecific rank. When he made these observations Emery had only 
two nest series for study, the type specimens from Pullman, Washington 
and other specimens from Utah. In these two series of workers Emery 
noted variations which partially negated the distinctions on which he 
based occidentalis. The antennal scapes of the Utah specimens were 
thicker than those of the Pullman types. The Utah specimens, there- 
fore, approached the typical subterranea very closely. If any long 
series of material belonging to occidentalis is examined, Emery's cri- 
teria appear very shaky. I am inclined to believe that occidentalis 
cannot be separated from the European form and I have allowed it 
to stand in the present volume only because I have been unable to 
examine an adequate amount of material belonging to the typical 
subterranea. When this can be done it seems virtually certain that 
the name occidentalis will have to go into the synonymy of subterranea. 

After the description of occidentalis in 1895 nothing more was done 
with this insect until 1915. In that year Wheeler described two ad- 
ditional variants, the subspecies borealis and valida. Two years later 
he added the variety manni, which was based on specimens taken in 
the type locality of occidentalis. The descriptions of all three of these 
variants are very confusing, since they embody contradictions in the 
definitive characters of the three forms. Particularly is this true of 
sculpture and color. The minor sculptural differences cited by Wheeler 
are wholly without significance because of the notable variations which 
occur within any ordinary nest series. It seems certain that Wheeler 
was unaware that the smaller workers of these insects are usually more 
heavily sculptured than the large ones. It is obviously impossible to 
draw any fine sculptural distinctions under such circumstances. Much 
the same objection may be raised to the slight color differences which 
Wheeler cited; there is usually too much variation within a nest series 
to permit their certain application. In the course of this study the 
writer has examined the types of all of Wheeler's forms. Using these 
in conjunction with a very large number of specimens coming from 
more than fifty localities, I have reached the conclusion that in the 
New World subterranea is represented by only two forms. The first 



15U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

is the insect which Emery called occidentalis. The second is Wheeler's 
subspecies valida. Distributional studies of these two insects show 
that they are western and eastern races. The range of occidentalis lies 
largely in the mountains of the Pacific coast states. It begins in central 
California and runs northward .through Oregon and Washington into 
southern British Columbia. An eastern extension of this range carries 
the insect into the mountains of eastern Nevada. The subspecies 
valida is found in the Rocky Mountain region from central Colorado 
north through Wyoming and western Montana into southern British 
Columbia. The western boundary of the range of valida lies in the 
mountains of Utah. While it approaches the eastern end of the range 
of occidentalis in this region, there is little evidence that the two 
subspecies intergrade there. The area of intergradation is in the 
northern part of the range of each subspecies. It includes southern 
British Columbia, eastern Washington, northern Idaho and western 
Montana. In this region the variability of these insects is greatly 
increased. It is significant that three of the four described variants 
have come from this region. The differences which separate occidentalis 
and valida have been given in the key but it may be well to add that 
such differences can only be used with certainty when there is a con- 
siderable series of specimens available for examination. It is usually 
quite impossible to decide whether isolated workers belong to occi- 
dentalis or valida. There follows the synonymy of A. (Attomyrma) 
subterranea occidentalis Emery: 

A. subterranea subsp. occidentalis Emery, Zool. Jahrb. Syst., Vol. 8, p. 301 

(1895) 9. 
A. subterranea subsp. borealis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 412(1915) 9. 
A. subterranea subsp. valida var. manni Wheeler, Proc. Amer. Acad. Arts Sci. 

Boston, Vol. 52, p. 516 (1917) 9 . 

Type loc: Pullman City, Washington. Types: none in this country. 
Range: mountains of California from the latitude of Sequoia National Park 

north to British Columbia and eastward through the mountains of Nevada. 

The nesting habits of occidentalis appear to be considerably more 
flexible than those of valida. It often founds its colonies in areas of 
moderately heavy cover, although it prefers open and rather dry nest 
sites. 



17. APHAENOGASTER (ATTOMYRMA) SUBTERRANEA VALIDA Wheeler 

A. subterranea subsp. valida Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
p. 414 (1915) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA lol 

Type loc: Cheyenne Canyon, Colorado Springs. Types: A.M.N.H., M.C.Z. 
Specimens in the collection of the M.C.Z. bearing cotype labels and 
coming from Arrowhead, British Columbia are not a part of the type series. 

Range: Rocky Mountain Region from central Colorado north to British 
Columbia and west to the mountains of Utah. 

The subspecies valida lives by preference in the Transition Zone. 
Its nests are usually found in dry and fully exposed situations. As 
Wheeler has noted, the colonies of valida are more populous than those 
of occidentalis. 



18. APHAENOGASTEH (ATTOMYRMA) TENNESSEENSIS (Mayr) 

Atta tennesseensis Mayr, Verb. Zool-bot. Ges. Wien, Vol. 12, p. 95 (1862) 9 . 
Aphaenogaster tennesseensis Mayr, Ibid., Vol. 36, p. 443 (1886) V . 
Stenamma tennesseensis Emery, Zool. Jahrb. Syst., Vol. 8, p. 301 (1895). 
Stenamma tennesseensis var. ecalcarata Emery, Ibid., Vol. 8, p. 301 (1895) V . 
Atta laevis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 743 (1862) 9 . 
Myrmica subrubra Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 336 (1867) 9 9 ; 

Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 365 (1886). 
Type loc: Tennessee. Types: none in this country. 
Range: New England south to the eastern Gulf States and west to Wisconsin, 

Missouri and eastern Oklahoma. 

Emery distinguished the variety ecalcarata on the rather unusual 
basis that it possessed shorter and thicker spurs on the hind tibiae 
with the hairs on these parts more even. There would seem to be no 
reason to recognize this form. It certainly is not a northern race and 
the distinctions are so slight that it may be wondered why Emery 
chose to name it. 



19. APHAENOGASTER (ATTOMYHMA) TEXANA Emery 

The fact that Emery originally assigned iexana to fulva has un- 
doubtedly caused confusion in the case of this species. But this will 
not account for all the difficulties which have beset the taxonomy of 
this insect. After it was recognized that the head of texana is narrow, 
both in the worker and female, this fact was used as the basis for 
assigning to texana variants described from minims only. Since the 
minims of other species may also show this trait and since nearly all 
minims fail to show the definitive characters of their respective species, 
this practice is thoroughly deplorable. The naming of the forms nana 
Wheeler, punctithorax Cole and pusilla Emery has been wasted effort. 
Since the type series of all three forms consisted only of minims, it 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



will be impossible to determine what they actually represent. I pro- 
pose, therefore, to discard the above three forms as impossible of exact 
recognition. 

There remain the variants carolinensis, furvescens and silvestrii, the 
last having been described by Menozzi as a separate species 1 . If one 
had to deal only with the type material of these variants, it would be 
easy to believe that they represent three geographical races of the 
typical texana. For carolinensis comes from North Carolina, silvestrii 
from Florida and furvescens from Arizona. But when additional ma- 
terial is examined, this view will not hold. Because of the rather 
spotty character of the distribution of texana, it is difficult to evaluate 
the status of some of the variants but enough material has now been 
accumulated to show that the color variety furvescens cannot be re- 
garded as a geographical race. Dark colored individuals are known to 
occur over the entire range of texana. Conversely, light colored speci- 
mens may be found in the western portions -of the range, where 
furvescens should replace them if it were a valid subspecies. The 
variant silvestrii is known from so little material that its relationship 
to texana is doubtful. Wheeler regarded this form as a synonym of 
furvescens and it certainly cannot be defended as a separate species. 
Yet, since the typical texana occurs in the same stations, it is equally 
hard to consider it as a valid subspecies. In this work both furvescens 
and silvestrii have been synonymized with the typical texana. 

The one remaining variant, carolinensis, shows certain character- 
istics which indicate that it is a true geographical race. This variant 
occurs as far north as southwestern Virginia. Its range appears to 
follow the Piedmont and lower Appalachian levels as far south as 
northern Alabama. The typical texana, whose northern range barely 
enters North Carolina, is usually found in the coastal plain area. This 
elevational difference is not great enough to bring about a complete 
separation of the two forms, hence there is some intergradation in the 
southern Atlantic and eastern Gulf states. On the other hand, there 
are several areas in the Piedmont where there are "pure stands" of 
carolinensis. In this respect it differs from any other described variant 
and for this reason it has been retained as a valid subspecies. There 
follows the synonymy of A. (Attomyrma) texana Emery: 

A. fulva var. texana Emery, Zool. Jahrb. Syst., Vol. 8, p. 306 (1895) 9 . 

A. texana Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 412 (1915) 9 9 d". 

A. texana var. furvescens Wheeler, Ibid., Vol. 34, p. 413 (1915) 9 . 

1 In the same year that Menozzi described silvestrii (1929), Wheeler published a paper 
carrying the description of an Aphaenogaster from Funkiko, Formosa bearing the same name. 
As Menozzi's name has a priority of three months, I suggest the n&mefunkikoensis for Wheeler's 
homonym. 



CREIGHTON: ANTS OF NOKTH AMERICA loo 

A. (Deromyrma) silvestrii Menozzi, Bull. Lab. Zool. Portici, Vol. 22, p. 282, 

fig. 1 (1929) 9 9 . 

Type loc: Texas. Types: none in this country. 
Range: Arizona through Texas to the eastern Gulf and south Atlantic states. 

There appear to be no records of texana from New Mexico, although the 

insect must certainly occur there. 



20. APHAENOGASTER (ATTOMYRMA) TEXANA CAROLINENSIS Wheeler 

A. texana subsp. carolinensis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 414 (1915). 
Type loc: Tryon, North Carolina. Types: A.M.N.H., M.C.Z., Coll. W. S. 

Creighton. 
Range: Piedmont region from southwestern Virginia to northern Alabama. 



21. APHAENOGASTER (ATTOMYRMA) TREATAE Forel 

A. treatae Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 40 (1886) 9 9 cf; 

Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 443 (1886). 
Stenamma treatae Emery, Zool. Jahrb. Syst., Vol. 8, p. 302 (1895) 9 . 
A. (Attomyrma) treatae M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 554, pi. 6, fig. 23 (1947) 9 . 

A. treatae subsp. wheeleri Mann, Psyche, Vol. 22, p. 51, fig. 16 (1915) 9 9. 
A. (Attomyrma) treatae var. alabamensis G. C. & E. W. Wheeler, Psyche, 

Vol. 41, No. 1, p. 11 (1934) 9 9. 
Range : southern New England to Florida and the eastern Gulf states. In the 

north central states the main range apparently terminates in Ohio. The 

records from areas further west are decidedly sporadic although the insect 

has been taken as far west as Illinois. 



I have synonymized Mann's subspecies wheeleri with treatae since 
it seems impossible to regard this variant as a geographical race. In 
the original description of wheeleri, Mann presented an imposing list 
of differences which supposedly mark that insect. After an exami- 
nation of the types of wheeleri and also of a large amount of material 
taken on Naushon Island, the type locality of wheeleri, it appears that 
most of these differences are not sufficiently constant to permit a 
satisfactory separation. Certainly they have no particular geographi- 
cal significance for it is possible to find specimens referable to wheeleri 
over most of the range of treatae. A different situation obtains in the 
case of the variety alabamensis. The types of this insect were taken 
by the writer at Ft. Payne, in northern Alabama. In sculpture and in 
the shape of the antennal lobe the insect is clearly intermediate be- - 



lo4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

tween the typical treatae and pluteicornis. Indeed, this was noted at 
the time of its original description. Since the type locality of ala- 
bamensis lies in a region where the range of treatae might be expected 
to meet that of its western race, pluteicornis, there is no reason why 
alabamensis should not be regarded as an intergrade between treatae 
and pluteicornis. It is rather unfortunate that it should have been 
given a varietal name. 



22. APHAENOGASTER (ATTOMYRMA) TREATAE PLUTEICORNIS 
G. C. and E. W. Wheeler 

.4. (Attomyrma) treatae subsp. pluteicornis G. C. & E. W. Wheeler, Psyche, 

Vol. 41, No. 1, p. 7, figs. 1 a, b (1934) 9 9 d*. 
A. (Attomyrma) treatae subsp. pluteicornis var. oklahomensis G. C. & E. W. 

Wheeler, Ibid., Vol. 41, p. 10, fig. 1 c, d (1934) 9 . 
Type loc: Poteau, Oklahoma. Types: Coll. G. C. Wheeler, Coll. W. S. 

Creighton. 
Range: Oklahoma to eastern Texas and southern Alabama. 

In describing the variety oklahomensis, the Wheelers noted that 
several of the definitive characteristics were prone to vary. About the 
only satisfactory distinction which was given was the paler color. An 
examination of the types of both pluteicornis and oklahomensis, which 
the Wheelers very generously sent to me, has convinced me that 
oklahomensis is no more than a color variety of pluteicornis. Very 
little is known about the range of oklahomensis but the fact that both 
it and pluteicornis were taken at Poteau, Oklahoma, argues against 
the possibility that oklahomensis is a geographical race. In my opinion 
it is best treated as a synonym of pluteicornis. 



23. APHAENOGASTER (ATTOMYRMA) UINTA Wheeler 

.4. uinta Wheeler, Proc. Amer. Acad. Arts Sci. Boston, Vol. 52, p. 517 

(1917) 9 9 <? . 
Type loc: East Mill Creek, Salt Lake County, Utah. Types: M.C.Z., 

A.M.N.H., Coll. W. S. Creighton. 
Range: southern Utah and southwestern Colorado north to -Idaho. 

This insect prefers to nest in fully exposed areas of great aridity. 
It is one of the few ants that appear to thrive in the immediate vicinity 
of Great Salt Lake. 



CKEIGHTON: ANTS OF NORTH AMERICA loo 

Genus NoVOMESSOR Emery 
(Plate 19, figures 1-4) 

The habits of the ants belonging to the genus Novomessor were 
discussed in a paper published by Dr. W. M. Wheeler and the writer 
in 1934. The two species which occur in western Texas and the 
southern portions of New Mexico and Arizona are large and con- 
spicuous insects with habits which differ rather notably from those of 
many xerophilous genera. The insects are remarkably deliberate in 
their movements. When foraging they stalk slowly about and show 
little sign of excitement, even when disturbed. During the summer 
months much of the foraging is done at night. The ants usually return 
to the nest during the forenoon and remain in it until the heat of the 
day is over. The nests are extraordinary. The main nest passage 
usually consists of a shaft three or four inches in diameter. The walls 
of this shaft are very rough and it is ordinarily rather crooked. It 
looks more like a rat's burrow than the entrance to an ant's nest. If 
the nest is free in the soil, as is almost always the case with those of 
cockerelli, there is a large but thin disc of gravel spread around the 
opening. The discs of albisetosus are smaller than those of cockerelli 
and albisetosus will sometimes nest under stones, which cockerelli rarely 
does. Both species appear to be omnivorous and there is little to 
indicate that they harvest seeds, as so many desert-dwelling species do. 
The nests of cockerelli are usually situated on flats at the base of desert 
ranges. Those of albisetosus are more often found on the lower slopes 
of such ranges. 

Key to the species of Novomessor 

1. Head, exclusive of the mandibles, slightly or not at all longer than broad 
with wavy, longitudinal rugae extending almost to the occipital border, the 

occipital area granulose albisetosus 

Head, exclusive of the mandibles, at least one and one-third times as long 
as broad with the wavy longitudinal rugae well-developed only in the 
anterior half of the head; the posterior half with much feebler rugae which 
are replaced towards the occiput with fine, coriaceous sculpture . . . cockerelli 



1. NOVOMESSOR ALBISETOSUS (Mayr) 

Aphaenogaster albisetosus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 446 

(1886) 9. 
N. albisetosus Emery, Rend. Accad. Sci. Bologna, p. 731 (1915); Emery, in 

Wytsman Genera Insectorum, Fasc. 174, pi. 1, fig. 16 (1921) a"; Wheeler 

and Creighton, Proc. Amer. Acad. Arts Sci. Boston, Vol. 36, p. 349, pi. 1, 

fig. 3 (1934) 9 9 d". 



loo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

A r . cockerelli var. minor Enzmann, Jour. N. Y. Ent. Soc., Vol. 55, No. 2, 
p. 148, pi. 8 (1947) ? . 

Ischnomyrmex albisetosus Wheeler, Ants, Columbia Univ. Press, p. 280 (1910). 

Type loc: New Mexico. Types: none in this country. 

Range: southwestern Texas to southern Arizona. Although there appear to 
be no Mexican records for this species, it must occur in the highlands of 
Chihuahua. It is abundant in the Chisos Mountains and can scarcely be 
absent from the barren Sierra del Burro which lies just across the Rio 
Grande a few miles to the south. 

There are several highly confusing points concerning the insect 
which Miss Jane Enzmann described in 1947 as Novomessor cockerelli 
var. minor. The type locality was given as Corpus Christi. It is 
unthinkable that a representative of Novomessor should occur at sea 
level and hundreds of miles to the east of its range. Nevertheless the 
figure which Miss Enzmann presented is clearly that of Novomessor 
albisetosus. I have taken the view that in this case the figure is more 
reliable than the locality record. It should be borne in mind, however, 
that no reliance can be placed on Miss Enzmann's work. She has 
thrown together in a single key, species belonging to the genera 
Novomessor, Veromessor and Aphaenogaster. No reason was given 
as to why this was done nor has any been supplied to explain why 
each genus is only partially represented. When I first examined this 
key I was inclined to believe that Miss Enzmann had rejected the 
revisionary proposals which W. M. Wheeler and I published for 
Novomessor and Veromessor in 1934. It seemed possible that she had 
returned to Emery's older view which held Veromessor to be a sub- 
genus of Novomessor. A further consideration of Miss Enzmann's 
work has forced me to a much more distasteful conclusion. I believe 
that there are no revisionary implications in Miss Enzmann's key and 
that its peculiar character is an outcome of a total lack of appreciation 
for the definitive features of the species involved. The key is wholly 
without merit and is a stumbling block in the path of those seeking 
an acquaintance with the species covered. It is mentioned here only 
because there seems to be no other way of countering the damage 
which this wretched piece of taxonomic work may do. 



2. NOVOMESSOR COCKERELLI (E. Andre) 

Aphaenogaster cockerelli E. Andre, Rev. Ent., p. 150 (1893) 9 . 

N. cocquerelli Emery, Rend. Accad. Sc. Bologna, p. 73 (1915). 

N. cockerelli Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, Vol. 36, 

p. 352, pi. 1, fig. 1, 4 (1934) 9 9 cf; M. R. Smith, Amer. Mid. Naturalist, 

Vol. 37, No. 3, p. 554, pi. 6, fig. 24 (1947) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA 15 

Ischnomyrmex cockerelli Wheeler, Ants, Columbia Univ. Press, p. 280, fig. 155 

(1910) 9 9 c?. 
Aphaenogaster sonorae Pergande, Proc. Calif. Acad. Sci. (2), Vol. 4, p. 34 

(1895) 9. 

Type loc: Montezuma, Chihuahua, Mexico. Types: none in this country. 
Range: western Texas to southern Arizona and south into Mexico. 



Genus VEROMESSOR Forel 
(Plate 20, figures 1-4) 

There is much discrepancy in our knowledge of the five species of 
Veromessor which occur in the United States. Two of the species, 
V. andrei and V . pergandei, are well known insects, which are repre- 
sented in American collections by abundant material. They have been 
repeatedly studied in the field and the literature contains several 
accounts of their habits. In contrast, the species stoddardi, chamberlini 
and lobognathus are known from exceedingly limited material. Not 
only are they poorly represented in collections but their habits are very 
imperfectly understood or entirely unknown. The following account 
is, of necessity, based on the habits of andrei and pergandei. 

Both these species produce flourishing colonies. They are active 
ants and harvest large quantities of seeds. The nests of pergandei are 
usually surmounted by a mound or crater of excavated soil. Those of 
andrei may or may not have a mound. If no mound is present there 
is usually an irregular disc of gravel around the nest entrance. V. per- 
gandei will usually make a neat pile of chaff with the husks of the 
seeds which it has stored in its nest. This chaff pile may be semicircular 
or it may form a ring which completely encircles the nest. V. andrei 
also makes chaff piles at the entrance to the nest but these are generally 
more ragged than those of pergandei and not infrequently andrei will 
scatter the chaff about, without attempting to build it into a pile. 

Both Wheeler (1910) and Cole (1934) have observed that the major 
harvesting activities of pergandei take place in the early morning and 
the late afternoon. During these periods long files of workers leave 
the nest and gather seed from the surrounding vegetation. Towards 
midday the foraging columns dwindle but the activity of the ants in 
the vicinity of the nest continues during the noon hours. Excavated 
soil is added to the mound and seed husks are brought out of the nest 
and placed on the chaff pile. In the writer's opinion, V. pergandei 
shows much less tendency toward midday estivation than do many of 
our desert species. It would appear that pergandei exhibits this re- 
sponse only when the temperature is exceptionally high. The ordinary 



loo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

midday temperatures during the summer months seem to have little 
effect on this species. The writer has observed it working outside the 
nest in the southern Mojave Desert during the midday hours in early 
August. Mallis (1941) has reported similar observations. The large 
number of records for this species from areas of high temperature and 
exceptional aridity show that pergandei can endure extreme desert 
conditions. It appears to be at home not only in the Mojave Desert 
but in the even hotter Imperial Desert as well. Any species which can 
live in the latter area may certainly qualify as a fully developed 
xerophile. V. andrei is much less xerophilous. Although it occurs 
along the northern periphery of the Mojave Desert, it seems unable 
to tolerate the more drastic conditions which occur to the south. 



Key to the species of Veromessor 

1. Head largely or entirely covered with coarse, wavy, longitudinal rugae, the 

interrugal spaces coriaceous or granulose 3 

Head entirely covered with fine longitudinal striae which are interrupted 
by punctures 2 

2. Dorsum of the pronotum without striae, the surface delicately shagreened 

and strongly shining; color black or piceous brown pergandei 

Dorsum of the pronotum longitudinally striate, feebly shining; color 
reddish brown stoddardi 

3. Rugae at the midline of the head approximately straight and not diverging 
behind; the interrugal spaces over the entire head strongly coriaceous, the 

surface dull lobognathus 

Rugae at the midline of the head as coarse and wavy as those elsewhere 
and distinctly diverging behind; the interrugal spaces granulose and feebly 
shining 4 

4. Proximal portion of the antennal scape ending in a flattened, spatulate lobe ; 

head as broad as long chamberlini 

Proximal portion of the antennal scape ending in a trumpet-like flange; 
head longer than broad 5 

5. Antennal scapes in repose just reaching the occipital border; color blackish 

red to clear red andrei 

Antennal scapes in repose slightly surpassing the occipital border; color 
castaneous brown to brownish yellow andrei subsp. castaneus 



1. VEROMESSOR ANDREI (Mayr) 

Aphaenogaster andrei Mayr,Verh. Zool-bot. Ges. Wien, Vol. 36, p. 443 (1886) 9 . 
Stenamma (Messor) andrei Emery, Zool. Jahrb. Syst., Vol. 8, p. 306 (1895) 9 . 
Novomessor andrei Emery, Rend. Accad. Sci. Bologna, p. 73 (1915). 



CREIGHTON: ANTS or NORTH AMERICA low 

Novomessor (Veromessor) andrei Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 51, 

p. 235 (1917). 
Veromessor andrei Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 36, p. 362, pi. 2, fig. 2 (1934) 9 . 
Type loc: California. Types: none in this country. 
Range: California, from the San Diego region to the Oregon border with an 

eastern extension north of the Mojave Desert which runs through Nevada 

into northwestern Arizona. 



2. VEROMESSOR ANDREI CAS 



Wheeler and Creighton 



V. andrei subsp. castaneus Wheeler and Creighton, Proc. Amer. Acad. Arts 

Sci. Boston, Vol. 36, p. 365 (1934) 9 . 

V. andrei subsp. flavus Wheeler and Creighton, Ibid., p. 366 (1934) 9 . 
Type loc: Jucumba, California. Types: M.C.Z., Coll. W. S. Creighton. 
Range: known only from the San Diego region in California. 

The status of castaneus is at present problematical. I have at- 
tempted to improve the existing situation by making flavus a synonym 
of castaneus for it now seems clear that both these forms cannot be 
considered as valid subspecies. Both occur in the same area in southern 
California, but this difficulty is more easily handled than the fact that 
the typical andrei occurs there also. There is no doubt that castaneus 
differs in structure from the typical andrei but these differences are 
scarcely what one would expect in the case of a separate species. The 
largest workers of castaneus are smaller than those of andrei, the 
antennal scapes of castaneus are longer, its epinotal suture is less 
deeply impressed and the ventral tooth and lamella on the petiole are 
small or absent. These differences are what would be expected of a 
subspecies. Since it is entirely possible that the range of castaneus lies 
for the most part in Lower California, it may be provisionally retained 
as a subspecies until we know more of the ants of that region. 



3. VEROMESSOR CHAMBERLINI (Wheeler) 

Messor chamberlini Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 410 

(1915) 9. 
V. chamberlini Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 36, p. 366, pi. 2, fig. 5 (1934) 9 . 
Type loc: Santa Cruz Island, California. Types: M.C.Z., Coll. W. S. 

Creighton. 
Range: known only from type material. 



loll BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

4. VEROMESSOE LOBOGNATHUS (Andrews) 

Messor lobognathus Andrews, Psyche, Vol. 23, No. 3, p. 81 (1916) 9 . 

V. lobognathus Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 36, p. 371, pi. 2, fig. 6 (1934) 9 . 
Type loc: Glenwood Springs, Colorado. Type: M.C.Z. 
Range : nothing positive known, see below. 

Most of what is known about the range of lobognathus at present is 
highly perplexing. According to Andrews, the four workers which 
form the type series of lobognathus were taken by T. D. A. Cockerell 
at Glenwood Springs, Colorado. It is not surprising that Professor 
Cockerell should have turned up a new species of ant, for he frequently 
did so. But it is surprising that this species should have belonged to 
a genus which is so largely confined to California. Glenwood Springs 
lies about fifty miles to the west of the main chain of the Rockies. 
Yet there is a gap of five hundred miles which separates this station 
from the easternmost record of any other species belonging to Vero- 
messor. I found this fact so peculiar that in 1932 some time was spent 
trying to rediscover lobognathus at Glenwood Springs. My failure to 
find it there proves nothing, of course, except that the insect is not 
abundant in its supposed type locality. Lately, some even more 
peculiar data has come to light. I have seen three specimens of 
lobognathus which, if one can believe the locality label, were taken in 
Missouri. The record from Glenwood Springs was odd enough but the 
one from Missouri is simply beyond belief. We are badly in need of 
accurate information on the distribution of lobognathus and, until such 
information can be obtained, there is little point in speculating on the 
range of this species. 



5. VEROMESSOR PERGANDEI (Mayr) 

Aphaenogaster pergandei Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 444 

(1886) V. 

Slenamma (Messor) pergandei Emery, Zool. Jahrb. Syst.,Vol. 8, p. 307 (1895) 9 . 
Novomessor pergandei Emery, Rend. Accad. Sci. Bologna, p. 73 (1915). 
Novomessor (Veromessor) pergandei Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 51, 

p. 234 (1917). 
V. pergandei Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 36, p. 347, pi. 2, fig. 3 (1934) 9 9 cf; M. R. Smith, Amer. Mid. 

Naturalist, Vol. 37, No. 3, 
Type loc: California. Types: worker, none in this country; female and male, 

M.C.Z., Coll. W. S. Creighton. 
Range: deserts of southwestern Arizona, southern California and Lower 

California. 



CKEIGHTON: ANTS OF NOKTH AMERICA Ibl 

6. VEROMESSOR STODDARDI (Emery) 

. Stenamma (Messor) stoddardi Emery, Zool. Jahrb. Syst., Vol. 8, p. 307 (1895) 9 . 
Novomessor (Veromessor) stoddardi Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 51, 

p. 235 (1917). 
V. stoddardi Wheeler and Creighton, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 36, p. 385, pi. 2, fig. 1 (1934) 9 . 
Type loc: San Jacinto, California. Types: U.S.N.M., M.C.Z., Coll. W. S. 

Creighton. 
Range: known only from the San Diego region of California. 



Genus PHEIDOLE Westwood 
(Plate 21, figures 1-6) 

Unlike most large myrmicine genera, Pheidole has not yielded easily 
to subgeneric division. Although at least eight subgenera have been 
recognized, all of them have been small groups. The eight taken to- 
gether contain less than ten percent of the species. Thus more than 
ninety percent of the several hundred species still remain in the sub- 
genus Pheidole. When Emery published the first myrmicine section 
of the Genera Insectorum in 1921 he attempted to improve this situation 
by dividing the subgenus Pheidole into twelve groups. It is not often 
that Emery placed expediency ahead of phyletics but in this case the 
desperate complexity of the subgenus Pheidole seems to have driven 
him to do so. The recognition of these groups involves the joint use 
of distributional data and structure. At first sight the arrangement 
looks remarkably like many others which Emery advocated. There 
is, however, a distinct difference. In other genera Emery's groups are 
characterized by sufficient structural distinction to enable them to be 
recognized regardless of the zoogeographical region where they occur. 
Hence the same group may be present on two or more continents and 
its recognition does not depend on its geographical affinities. This 
situation is reversed in the case of the groups in Pheidole. The major 
division is one of geography. The Old World species are separated 
from those of the New World and, within each of these two segments, 
subgroups based upon structure are set up. From a practical point of 
view this arrangement has its advantages but from a phyletic stand- 
point it is unsatisfactory. There is a sound reason why no attempt 
has been made to elevate Emery's groups into subgenera. No plan 
which rules out the possibility of relationship between Old and New 
World species is likely to find many champions however useful it 
may be. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



The writer doubts that Emery's arrangement is of much service 
from a practical point of view. I have found it virtually impossible to 
utilize the distinctions on which Emery based his groups as major key 
splits. I do not doubt that this could be done, but it would involve 
the peculiar situation in which the distinctions between species are 
more striking than those which separate the major groups. For this 
reason I have made no attempt, either in the key or in the body of 
the text, to utilize Emery's groups to distinguish our species. Anyone 
who is interested in a group arrangement should consult the Genera 
Insectorum (Ease. 174) where Emery's plan may be studied in detail. 
The alternative has been to construct a single, very long key covering 
all our species. I admit that the length of this key is objectionable 
but I have been assured by people who have tried it that it works. 
If so, it fulfills the principal function for which it was designed. If 
anyone ever undertakes the herculean task of monographing the genus 
Pheidole, we may be able to improve the present situation and base 
our keys on phyletic characteristics. Until that time it seems best to 
treat the subgenus Pheidole as a single unit. 

Most of our species of Pheidole possess a dimorphic worker caste 
with the major and minor workers not connected by intermediates. 
In a few species, however, the worker caste is polymorphic (kingi 
instabilis and torpescens, vasliti arizonica, etc.). Most of the species 
garner seeds and it is believed that the large-headed major workers 
function as seed-huskers. The enlarged head of the major is mainly 
filled with mandibular muscles. This enables the jaws to exert much 
pressure, which should be useful in cracking off the husks of seeds. 
It may be added that sometimes the head of the major is so large in 
proportion to its body that if the insect is turned over on the back of 
its head it cannot regain a normal posture without help from other 
workers. Despite their preference for a graminivorous diet many 
species of Pheidole will accept other food as well. They seem less 
attracted to honey-dew than do many ants but will often feed vo- 
raciously on animal tissue when the opportunity offers. The majority 
of our species form small colonies. In many cases there are only about 
two or three hundred individuals in a fully developed nest. Even in 
the case of the species which produce comparatively large nests 
(morrisi, hyatti, desertorum etc.) a colony of more than two or three 
thousand individuals would be exceptionally large. By far the ma- 
jority of our species nest in soil. The nest may be built under a stone 
or in open soil without a covering object. In the latter case there is 
often a mound or crater of excavated soil surrounding the nest entrance. 
The eastern species dentata will nest in rotten logs as well as soil but 
such flexibility in nesting habit is exceptional. 



CEEIGHTON: ANTS OF NORTH AMERICA 



Key to the species of Pheidole 

1. Gaster not truncate at the base (Subgenus Macropheidole) rhea 

Gaster truncate or subtruncate at the base (Subgenus Pheidole) 2 

2. Head of the major cylindrical in cross-section and obliquely truncated in 

front lamia 

Head of the major not cylindrical in cross-section and not obliquely 
truncated in front 3 

3. Scapes of the major reaching or surpassing the occipital angles 4 

Scapes of the major not reaching the occipital angles ! 

4. Upper surface of the head of the major densely granulo-rugose and dull; 

epinotal spines slender and directed upward grallipes 

Upper surface of the head of the major with prominent longitudinal rugae, 
the interrugal spaces not granulose or at most very feebly granulose with 
the surface shining; epinotal spines thick at the base and directed back- 
ward desertorum 

5. Antennal scape of the major laterally bent at the base so that the scape 
turns toward the midline of the head in passing to the antennal socket, 

the flattened basal portion as wide as the distal part of the scape 6 

Antennal scape of the major not laterally bent at the base or, if slightly 
bent and flattened, the flat part is not as wide as the distal portion of the 
scape 1< 

6. Antennal scape of the major reaching three-quarters or more of the 

distance between its insertion and the occipital angle 7 

Antennal scape of the major reaching two-thirds or less of the distance 
between its insertion and the occipital angle 11 

7. The entire upper surface of the head of the major covered with reticulo- 

rugose sculpture, the interrugal spaces granulose 8 

The reticulo-rugose sculpture largely confined to the anterior half of the 
head in the major, the occipital lobes punctate or feebly granulose, the 
surface moderately to strongly shining at least in the posterior half of 
the head 9 

8. Head of the minor densely sculptured and completely opaque; the post- 
petiole transversely oval and twice as wide as the node of the petiole . . . 

texana 

Head of the minor in part strongly shining, the sculpture nowhere very 
dense; the postpetiole globular and less than twice as wide as the node of 
the petiole cockerelli 

9. Head of the minor densely punctate, opaque; erect hairs on the gaster of 

the major sparse and widely spaced vatticola 

Head of the minor smooth and shining; erect hairs on the gaster of the 
major numerous, long and closely spaced 10 

10. Head of the major measuring 1.4 mm. x 1.3 mm.; female 7 mm. in length 

hyatti 

Head of the major measuring 1.2 mm. x 1.1 mm.; female 5 mm. in length 

hyatti subsp. solitanea 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



11. The occipital lobes of the major striato-granulose and scarcely shining. . 

vasliti subsp. arizonica 1 

The occipital lobes of the major strongly shining and bearing piligerous 
punctures only 12 

12. The flattened basal portion of the scape of the major notably broader 

than the distal portion porcula 

The flattened basal portion of the scape of the major no wider than its 
distal portion 13 

13. Erect gastric hairs, when present, much longer and coarser than the fine 

appressed pubescence crassicornis 

Erect gastric hairs very numerous, rather short and so fine that they 
merge with the pubescence most of which is semierect 

crassicornis subsp. tetra 

14. The tops of the occipital lobes of the major, and usually their front faces 
as well, covered with sculpture, the surface opaque or feebly shining. . 15 
The tops of the occipital lobes of the major, and usually their front faces 
as well, free from sculpture except for piligerous punctures, the surface in 
most cases strongly shining 30 

15. The anterior margin of the clypeus of the major with a deep, semicircular 
impression which extends inward almost to the level of the frontal 

lobes 16 

The anterior margin of the clypeus of the major entire, or if impressed 
the impression is shallow and not semicircular 17 

16. Head of the major with parallel sides except for a very slight narrowing 

in front of the eyes kingi subsp. instabilis 

Head of the major notably narrowed in its anterior half 

kingi subsp. torpescens 

17. Humeral angles of the pronotum of the major feebly developed and not 

forming lateral bosses 18 

Humeral angles of the pronotum of the major strongly developed and 
forming distinct, epaulet-like lateral bosses 20 

18. Posterior half of the head of the minor without sculpture except for 

piligerous punctures sitarches 

Posterior half of the head of the minor striate or densely punctato- 
granulate 19 

19. Head of the minor striate posteriorly sitarches subsp. soritis 

Head of the minor punctate posteriorly sitarches subsp. campestris 

20. Postpetiole in the major lenticular, the lateral connules well-developed . . 21 
Postpetiole in the major trapezoidal, the lateral connules absent or poorly 
developed 26 

21. Occipital sculpture of the major reticulate with no trace of transverse 

rugae or striae; head of the major 0.85 mm. in length dentigula 

Occipital sculpture of the major, even when reticulate, with the rugae so 

1 The strongly polymorphic worker caste of arizonica is a source of considerable confusion. 
The larger medias would run out in the key to hyatii or cockerdli, from which they would differ 
through the more rugose occipital lobes. The smaller medias approach the condition found in 
the major of desertorum but have shorter and more numerous erect hairs on the thorax and 
gaster. The minors are almost impossible to distinguish from those of hyatti. 



CREIGHTON: ANTS OF NORTH AMERICA 



arranged that they appear as transverse ridges; head of the major 1.4 mm. 
or more in length 22 

22. Transverse rugae on the occiput of the major prominent and usually 

extending well onto the front face of the lobes 23 

Transverse rugae on the occiput of the major feeble, sometimes replaced 
by transverse rows of small granules, the transverse sculpture in either 
case largely confined to the top of the occiput 25 

23. Interrugal sculpture on the front and vertex of the major consisting of 

dense granulations only tepicana subsp. cavigenis 

Interrugal sculpture on the front and vertex of the major consisting of 
coarse, oval foveae as well as granulations 24 

24. Head of the major with longitudinal rugae extending entirely across the 
vertex; interrugal spaces on the vertex finely punctured and scarcely 

shining pilifera 

Head of the major with the longitudinal rugae not crossing the vertex, 
the latter area distinctly shining with sparse, coarse punctures 

pilifera subsp. artemisia 

25. The portion of the head of the major in front of the occipital lobes with 
numerous, coarse foveae and granulations, the surface at most feebly 

shining pilifera subsp. coloradensis 

The portion of the head of the major in front of the occipital lobes with 
only small, piligerous punctures, the surface strongly shining 

pilifera subsp. pacifica 

26. Occipital rugae of the major turning forward onto the cheeks and con- 
tinuing across them to the insertion of the mandibles 

calif arnica subsp. micula 

Occipital rugae of the major not turning forward onto the cheeks, the 
latter shining, punctate but not striate 27 

27. Sides of the epinotum in the major granulose, feebly shining or opaque . . 28 
Sides of the epinotum in the major not granulose, very smooth and 
shining californica subsp. pyramidensis 

28. Occipital rugae in the major coarse and wavy, usually forming reticulations 

in the occipital sulcus 29 

Occipital rugae in the major finer, straight or nearly so and not usually 
forming reticulations in the occipital sulcus . . californica subsp. oregonica 

29. Hairs on the petiole and postpetiole of the major little or no longer than 

those elsewhere californica 

Hairs on the petiole and postpetiole of the major notably longer than those 
elsewhere californica subsp. shoshoni 

30. Head, thorax and gaster of the minor, and often of the major as well, 

with distinct violaceous or bluish reflections 31 

Violaceous reflections not present 32 

31. Head of the minor in large part sculptured, only a narrow central strip 

smooth and shining metallescens 

Head of the minor largely smooth and shining 

metallescens subsp. splendidula 

32. Entire thorax of the minor densely covered with granulose sculpture and 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



completely opaque 33 

At least the top of the pronotum of the minor shining or, if the entire 
thorax is opaque, the promesonotum is longitudinally striate and not 
densely granulose 41 

33. Antennal scapes of the minor surpassing the occipital border by an amount 

twice as great as the length of the first funicular joint 3 

Antennal scapes of the minor just reaching the occipital border or, if they 
surpass it, the amount is no greater than the length of the first funicular 
joint 35 

34. Vertex of the major densely sculptured, opaque sciophila 

Vertex of the major largely smooth and shining, the sculpture consisting 
of scattered patches of fine punctures . . . sciophila subsp. semilaevicephala 

35. Postpetiole of the minor, seen from above, spherical 36 

Postpetiole of the minor, seen from above, not spherical 37 

36. Occipital lobes of the major smooth and shining davisi 

Occipital lobes of the major striate on their anterior portions. . .nuculiceps 

37. Antennal scapes of the minor just reaching the occipital border or sur- 
passing it by an amount much less than the length of the first funicular 

joint 38 

Antennal scapes of the minor surpassing the occipital border by an amount 
equal to the length of the first funicular joint 39 

38. Pronotum of the major with delicate transverse rugae in addition to the 

punctures; erect hairs short and blunt constipata 

Pronotum of the major punctate only; erect hairs long and pointed. . . . 

anastasii 

39. Postpetiole of the minor, seen from above, transversely oval . . . proserpina 
Postpetiole of the minor, seen from above, shaped like a truncated cone. 40 

40. Head of the minor subquadrate, the middle of the occiput slightly concave 

floridana subsp. lauta 

Head of the minor notably narrowed in its anterior half, the middle of 
the occiput flat floridana 

41. Epinotum of the major angular at the junction of the basal and declivious 

faces but the angles not produced into distinct teeth or spines 42 

Epinotum of the major armed with distinct teeth or spines 44 

42. Prothorax of the major with very well-marked humeri; the postpetiole 

with prominent lateral connules barbata 

Prothorax of the major without prominent humeri; the postpetiole without 
prominent lateral connules 43 

43. The abdominal pilosity largely limited to coarse erect hairs; length of the 

major 3.54 mm morrisi 

The abdomen with many fine subappressed hairs in addition to the coarse 
erect ones; length of the major 4-5 mm morrisi subsp. impexa 

44. Large species, the head of the major at least 2 mm. in length and usually 

more 45 

Small species, the head of the major not exceeding 1.5 mm. in length and 
usually less ' 50 

45. Pronotum of the major with transverse striae 46 

Pronotum of the major without transverse striae 47 



CREIGHTON: ANTS OF NORTH AMERICA 



46. Head of the major with the longitudinal rugae confined to the anterior 
half, the posterior half without sculpture except for small piligerous 

punctures virago 

Head of the major with the longitudinal rugae extending onto the anterior 
parts of the occipital lobes titanis 

47. Postpetiole of the major, seen from above, very strongly transverse, 
notably constricted behind, with the prominent lateral connules sharply 

pointed spadonia 

Postpetiole of the major, seen from above, only moderately transverse, 
not greatly constricted behind, with the lateral connules short and rather 
blunt 48 

48. Head of the major notably longer than broad (2.2 mm. x 1.6 mm.); the 
genae suddenly expanded just behind the insertion of the mandibles. . . . 

ridicula 

Head of the major very little longer than broad (2.2 mm. x 2.1 mm.) or 
broader than long; the genae not expanded above the insertion of the 
mandibles 49 

49. Head of the major with a flattened, rugose area extending rearward be- 
tween the frontal lobe and the eye; promesonotum angular in profile. . . . 

macclendoni 

Head of the major without the flattened area described above; prome- 
sonotum evenly rounded in profile militicida 

50. Sculpture on the head of the major extending to the vertex, only the 

occiput smooth and shining ceres 

Sculpture on the head of the major largely confined to the anterior half 
of the head, the posterior half smooth and shining 51 

51. Mesonotum of the major depressed below the adjacent portion of the 
pronotum so that in profile it forms a distinct step or angular projection 

between the pronotum and the epinotum dentata 

Mesonotum of the major not depressed below the adjacent portion of the 
pronotum, in profile the two forming an evenly curved outline which 
usually descends abruptly at the mesoepinotal suture 52 

52. Eyes of the major with 60 or more facets 53 

Eyes of the major with 40 or less facets 54 

53. Pronotum of the major with the transverse striae largely confined to the 

anterior face, the dorsum smooth and shining xerophila 

Pronotum of the major entirely covered with transverse striae, feebly 
shining or opaque xerophila subsp. tucsonica 

54. Vertex and occiput of the minor with small, close-set punctures which 
give the surface a notably duller appearance on those parts than elsewhere 

on the head 55 

Vertex and occiput of the minor as strongly shining or only slightly less 
shining than the rest of the head, the punctures widely scattered over the 
whole surface of the head 56 

55. Basal face of the epinotum of the major sculptured and opaque .... casta 
Basal face of the epinotum of the major in large part shining, its sculpture 
restricted to punctures near the mesoepinotal suture cerebrosior 



loo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

56. Basal face of the epinotum of the major free from sculpture and strongly 

shining humeralis 

Basal face of the epinotum of the major distinctly sculptured, feebly 
shining or opaque 57 

57. Sides of the epinotum in the minor largely free from sculpture and strongly 

shining tysoni 

Sides of the epinotum in the minor densely punctured, feebly shining or 
opaque 58 

58. Lateral connules of the postpetiole of the major prominent and sharp 

pointed pinealis 

Lateral connules of the postpetiole in the major blunt and not promi- 
nent 59 

59. Erect hairs on the thorax of the minor short, sparse and strongly clavate 

martidula 

Erect hairs on the thorax of the minor long, abundant and, although often 
blunt at the tip, not clavate 60 

60. Basal face of the epinotum in the major largely punctate, transverse 
striae, when present, confined to the area between the bases of the epinotal 

spines; rugae of the pronotum feeble or absent 61 

Basal face of the epinotum in the major largely covered with transverse 
striae, the punctures restricted to the region of the mesoepinotal suture; 
rugae of the pronotum coarse and prominent bicarinata 

61. Epinotum of the minor armed with thick, short spines 62 

Epinotum of the minor armed with angular teeth which are broad at the 
base and do not resemble spines bicarinata subsp. longula 

62. Major castaneous brown to piceous brown, minor sordid yellow to piceous 

brown bicarinata subsp. buccalis 

Major clear yellow to yellowish brown, minor usually clear yellow 

bicarinata subsp. vinelandica 



Subgenus MACROPHEIDOLE Emery 



1. PHEIDOLE (MACROPHEIDOLE) RHEA Wheeler 

Ph. rhea Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 452 (1908) 9 . 
Ph. (Macropheidole) rhea M. R. Smith, Proc. Ent. Soc. Wash., Vol. 45, No. 1, 

p. 7 (1943) 9 01 9 . 
Ph. fimbriata Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 403 (1915) 

(not Roger). 
Type loc: Nogales, Arizona. Types: female, Coll. Cornell Univ.; major and 

minor, U.S.N.M. 
Range: southern Arizona south into Mexico. 

The records for rhea indicate a rather surprising tolerance for ele- 
vation. The insect has been taken in stations as low as 3700 feet and 



CREIGHTON: ANTS OF NORTH AMERICA lot) 

as high as 7000 feet. The majority of the records are about 4000 feet. 
The insect prefers to nest on plateaus or among foot hills at the base 
of mountains. 

In a paper published in 1943 (loc. tit.) Dr. M. R. Smith has cleared 
up much of the confusion which surrounded Wheeler's treatment of 
this species. Although Wheeler described rhea from a single dealated 
female taken at Nogales, Arizona, he later synonymized the species 
with Roger's fimbriata. This was done through comparison with a 
series of specimens taken at Cuatolopaz, Vera Cruz, Mexico. This 
series contains major and minor workers as well as winged females. 
The association with fimbriata was, presumably, made on the basis of 
the worker and major. According to Dr. Smith, Wheeler later realized 
he had been in error in synonymizing the two species for, although he 
never corrected his mistake, he continued to use the name rhea in 
identifying specimens from Arizona and Mexico. Working in con- 
junction with Dr. L. G. Wesson, Dr. Smith was able to show that rhea 
is specifically distinct from another species of Macropheidole which 
occurs in Mexico. The long series of differences in female, major and 
minor which Dr. Smith presented leaves no room for doubt on this 
score. But it may be doubted that this Mexican species is the same 
as Roger's fimbriata. The latter insect was originally described from 
material taken at Rio Paraguay and while it seems to be fairly abun- 
dant in northern Argentina, Paraguay and southern Brazil, there is 
little to indicate that it has a continuous range through South and 
Central America which would connect it with the Mexican specimens. 
If Roger's types are still in existence the problem can be solved by 
consulting them. But until this can be done the possibility must be 
considered that Mexican material at present assigned to fimbriata may 
represent a third species of Macropheidole. The important point is, 
however, that Dr. Smith has shown that rhea is a valid species and 
that Wheeler's synonymy of this insect with fimbriata must be dis- 
regarded. 



Subgenus PHEIDOLE Westwood 



2. PHEIDOLE ANASTASII Emery 
(Introduced) 

Ph. anastasii Emery, Bull. Soc. Ent. Ital., Vol. 28, p. 44 (1896) 9 <4 ; Forel, 

Mitt. Naturh. Mus. Hamburg, Vol. 18, p. 78 (1901) 9 . 
Type loc: Jimenez, Costa Rica. Types: A.M.N.H. 
Range: (in the United States) southern Florida. 



1/U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Like several other tropical importations, anastasii has been reported 
from greenhouses in various parts of the east. It is only in southern 
Florida that this species finds congenial climatic conditions out-of- 
doors. It appears to be well established in that state. 

3. PHEIDOLE BAEBATA Wheeler 

Ph. barbata Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 448 (1908) 9 01. 
Type loc: Mojave Desert near Needles, California. Types: A.M.N.H., 

M.C.Z. 
Range: deserts of western Arizona and southeastern California. 



4. PHEIDOLE BICAKINATA Mayr 

In dealing with this species the writer has found it necessary to 
return to Forel's original view concerning the relationship of vinelandica 
to bicarinata. I believe that Forel was correct when he described 
vinelandica as a subspecies of bicarinata and its subsequent elevation 
to specific rank has been a hindrance to the correct understanding of 
this complex. In addition to this change, considerable synonymy has 
been necessary. Emery's subspecies laeviuscula I regard as an inter- 
grade between bicarinata and vinelandica. Wheeler's variety castanea 
belongs not to longula but to buccalis, of which it seems to be no more 
than an insignificant color phase. I consider Smith's hayesi as identical 
with the typical bicarinata. Since none of Mayr's types are present in 
this country, it is difficult to deal with the typical form. I believe that 
the association is correct, however, since there seems to be only a 
single race (the typical bicarinata) present in the north central states. 
Wheeler's cerebrosior, which was originally described as a subspecies of 
vinelandica has been treated as a separate species. I present below a 
summary of the arrangement followed in this volume: 

Ph. bicarinata Mayr 

= hayesi M. R. Smith 
subsp. buccalis Wheeler 

= var. castanea WTieeler 
subsp. longula Emery 
subsp. vinelandica Forel 

= subsp. laeviuscula Emery 

The above arrangement is not without its faults but it has one 
marked advantage. The forms which are recognized as valid behave 
as geographical races. They maintain a reasonable constancy of 



CREIGHTON: ANTS OF NORTH AMERICA 1/1 

structure over their respective ranges and intergrade where the ranges 
join. A clear appreciation of this fact is a great help in handling the 
confusing intermediate forms which are often encountered in this 
group. There follows the synonymy of Ph. bicarinata Mayr: 

Ph. Ucarinata Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 989 (1870) 21 ; 

Mayr, Ibidem, Vol. 37, p. 596 (1887) 21. 

Ph. hayesi M. R. Smith, Ent. News, Vol. 35, p. 251 (1924) 9 21. 
Type loc: Illinois. Types: none in this country. 
Range: Ohio west to Wyoming and Colorado. The southern border of the 

range appears to correspond roughly with the southern boundaries of 

Kansas and Missouri. The insect does not appear to occur west of the 

Rockies. 

5. PHEIDOLE BICAHINATA BUCCALIS Wheeler 

Ph. vinelandica subsp. buccalis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 454 (1908) 9 21 ? . 
Ph. vinelandica subsp. languid var. castanea Wheeler, Ibidem, Vol. 34, p. 405 

(1915) 9 21. 

Type loc: Ash Fork and Prescott, Arizona. Types: A.M.X.H., M.C.Z. 
Range: Arizona and southern Utah east to Texas. 

The subspecies buccalis intergrades with vinelandica in western 
Texas. Although the color of buccalis varies to some extent, even the 
lighter specimens are distinctly darker than vinelandica. It is also a 
somewhat smoother insect than vinelandica but the difference is not 
great and, since confusing exceptions are sometimes encountered, this 
character was not included in the key. 



6. PHEIDOLE BICARINATA LONGULA Emery 

Ph. vinelandica var. longula Emery, Zool. Jahrb. Syst., Vol. 8, p. 292(1895) 9 21 ; 

Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 453 (1908) 21. 
Ph. vinekmdica subsp. longula Wheeler, Ibidem, Vol. 34, p. 405 (1915). 
Type loc: Pueblo, Colorado. Types: A.M.N.H. 
Range: western Texas to southeastern Colorado. 

There are several puzzling features connected with longula. Its 
range is comparatively limited, with its northern end adjoining that 
of the typical bicarinata and its southern end reaching the area in 
which vinelandica and buccalis come in contact. The chances for 
intergradation are excellent, yet intergrades do not seem to be pro- 
duced. Subsequent study may prove longula to be a separate species, 



-. BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

but the structural differences shown by this variant are of such a minor 
nature that this seems very unlikely. 



7. PHEIDOLE BICARINATA VINELANDICA Forel 

Ph. vinelandica Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 45 (1886) 9 Qt 9 c? ; 
Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 458 (1886); Mayr, Ibidem, 
Vol. 37, p. 591 (1887) 9 01; Emery, Zool. Jahrb. Syst., Vol. 8, p. 292 
(1895); Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 348 (1901) 9 01 $ <? 
Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 453 (1908) 21. 

Ph. (Allopheidole) vinelandica Forel, Mem. Soc. Ent. Belg., Vol. 19, p. 237 
(1912). 

Ph. laeviuscula Emery, Zool. Jahrb. Syst., Vol. 8, p. 292 (1895) 9 01. 

Type loc: Vineland, New Jersey. Types: none in this country. Specimens 
bearing cotype labels in the A.M.N.H. are from Morgantown, N. C. and 
do not belong to the type series. They are part of the material on which 
Forel based his second description of vinelandica in 1901. 

Range: southern New Jersey to South Carolina, west to Ohio and southwest 
to Texas. The insect does not occur in the southern portions of the 
eastern Gulf States or in Florida. 



8. PHEIDOLE CALIFORNICA Mayr 

We are fortunate that there are present in American collections 
types of all the variants belonging to this complex except the typical 
calif arnica. This circumstance has undoubtedly saved this group from 
many of the difficulties which beset such aggregations elsewhere in the 
genus. It has reduced the need for revisionary work to a minimum. 
I have thrown the varieties incenata, satura and hagermani into the 
synonymy but, aside from these, all the other described variants seem 
valid. As to whether they should be treated as subspecies is a more 
difficult question. I have followed Emery and retained them in this 
category, since our present knowledge of their distribution does not 
conflict with such a view. It should be remembered, however, that 
three of the five forms are known from type material only. About all 
that can be said in such cases is that the areas in which the forms 
occur are widely separated and that there is nothing to indicate co- 
incidental ranges. It is possible that when we have a better knowledge 
of the range of some of these variants they may prove to be species 
rather than subspecies. Wheeler's subspecies micula, for example, is 
a very distinct insect and might be considered a species on the basis 
of structure alone. Since its range apparently lies well to the south 
of the rest of the group, it shows distinction in this respect also. The 



CREIGHTON: ANTS OF NORTH AMERICA 1(6 

complex appears to be a very attractive one from a chorological 
standpoint and it is to be hoped that someone will undertake a study 
of its characteristics in the field. There follows the synonymy of 
Ph. californica Mayr: 

Ph. californica Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 987 (1870) 9 21; 
Mayr, Ibidem, Vol. 37, p. 588 (1887); Emery, Zool. Jahrb. Syst., Vol. 8, 
p. 289 (1895); Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 406 
(1915) 9 21 9 . 

Ph. californica var. satura Wheeler, Ibidem, Vol. 34, p. 407 (1915) V 21. 

Ph. californica var. incenata Wheeler, Ibidem, Vol. 34, p. 407 (1915) 9 2t. 

Type loc: San Francisco, California. Types: none in this country. 

Range: California, from San Francisco south to Los Angeles. 

The varieties incenata and satura were both based on slight color 
differences. I have synonymized them because they appear to be 
without any geographical significance. Such color differences occur in 
all parts of the range of the typical californica and, in my opinion, 
Wheeler should never have named them. 



9. PHEIDOLE CALIFORNICA MICULA Wheeler 

Ph. californica subsp. micula Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 408 (1915) 9 21. 

Type loc: Miller Canyon, Huachuca Mts., Arizona. Types: M.C.Z, A.M.N.H. 
Range: known from type material only. 



10. PHEIDOLE CALIFORNICA OREGONICA Emery 

Ph. oregonica Emery, Zool. Jahrb. Syst., Vol. 8, p. 291 (1895) 9 01. 

Ph. californica subsp. oregonica Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 407 (1915) 9 21 9 . 
Ph. californica var. hagermani Cole, Ent. News, Vol. 47, No. 5, p. 120 

(1936) 9 21. 

Type loc: The Dalles, Oregon. Types: A.M.N.H., M.C.Z. 
Range: Washington, Oregon and northern Idaho. 

Cole's variety hagermani belongs to oregonica and not to the typical 
californica, as he supposed. I can see no significant difference between 
the types of hagermani and those of oregonica. 



11. PHEIDOLE CALIFORNICA PYRAMIDENSIS Emery 

Ph. californica subsp. pyramidensis Emery, in Wytsman, Genera Insectorum, 
Fasc. 174, p. 105 (1921) (nomen novum). 



4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Ph. californica subsp. nevadensis Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 34, p. 408 (1915) 9 21. (nee Forel). 

Type loc: Pyramid Lake, Nevada. Types: M.C.Z., A.M.N.H. 
Range: known only from type material. 

When Wheeler described this insect as nevadensis, he was unaware 
that Forel had applied the same name to a variety of the South 
American Ph. pubiventris in 1901. The mistake was later corrected by 
Emery who must, of course, be cited as the author of the species. 



12. PHEIDOLE CALIFORNICA SHOSHONI Cole 

Ph. californica var. shoshoni Cole, Ann. Ent. Soc. Amer., Vol. 26, No. 4, p. 618 

(1933) 9 01. 
Type loc: Snake River Canyon, Twin Falls, Idaho. Types: Coll. A. C. Cole, 

Coll. C. H. Kennedy. 
Range: known only from type material. 

Since I have not seen type material of shoshoni or specimens certainly 
referable to it, I hesitated to include this subspecies in the key. I 
believe, however, that it will key out properly on the characters given. 
This subspecies seems very similar to the typical californica and may 
later prove to be a synonym of it. 



13. PHEIDOLE CASTA Wheeler 

Ph. casta Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 454, pi. 26, figs. 

22, 23 (1908) 9 01. 

Type loo: Canyon of Rio Grande, Langtry, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



14. PHEIDOLE CERES Wheeler 

Ph. ceres Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 10 (1904) 9 01 9 cf . 
Type loc: Colorado Springs, Colorado (by present restriction). Types: M.C.Z. 
Range: foothills of the Rockies in eastern Colorado southwestward to northern 

Arizona. This insect has also been reported from the Davis Mountains 

of Texas but it seems to be very rare in that region. 

I have restricted the type locality of ceres to Colorado Springs in 
the hope that this may lead to a clearer concept of the species. Wheeler 
originally considered specimens from several localities as the types of 
ceres. These specimens are by no means uniform. Those coming from 



CEEIGHTON: ANTS OF NORTH AMERICA !. 

Boulder are more heavily sculptured than the specimens taken in 
southern and western stations. As to what these differences mean is 
not clear at present. The specimens from Boulder may represent a 
northern race of ceres but, as they seem to occur nowhere else, it is 
inadvisable to attempt this distinction until more is known of the 
range of this variant. Ph. ceres is the host for the workerless parasite 
Sympheidole elecebra. 

15. PHEIDOLE CEREBROSIOR Wheeler 

Ph. vinelandica subsp. cerebrosior Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 

34, p. 405 (1915) 9 21. 

Type loc: Tucson, Arizona. Types: A.M.N.H., M.C.Z. 
Range: known only from the deserts of southern Arizona. 

There is little reason why cerebrosior should have been related to 
vinelandica. The soldier of cerebrosior has a strongly transverse 
postpetiole in which the lateral connules are very pronounced. Neither 
feature occurs in vinelandica. The minor of cerebrosior has antennal 
scapes which slightly surpass the occipital border. Those of the minor 
of vinelandica fall just short of the occipital border. The minor of 
cerebrosior is also more heavily sculptured than that of vinelandica. 

16. PHEIDOLE COCKERELLI Wheeler 

Ph. cockerelli Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 464 (1908) 9 01. 
Type loc: Arroyo Pecos, Las Vegas, New Mexico (by present restriction). 

Types: A.M.N.H., M.C.Z. 
Range: deserts of Southern New Mexico and Arizona. 



17. PHEIDOLE CONSTIPATA Wheeler 

Ph. constipata Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 468 

(1908) 9 21 9 d 1 . 

Type loc: Austin and New Braunfels, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



18. PHEIDOLE CRASSICORNIS Emery 

Ph. crassicornis Emery, Zool. Jahrb. Syst., Vol. 8, p. 296 (1895) 21; Forel, 

Ann. Soc. Ent. Belg., Vol. 45, p. 350 (1901) 9 Ot cf. 
Ph. crassicornis var. diversipilosa Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 

24, p. 467 (1908) 9 21 9 . 



i/o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: Charlotte, North Carolina. Types: none in this country (see 

below). 
Range: the Carolinas southwestward to Texas. The insect has also been 

reported from eastern Colorado but it is very rare in that state. 

There are specimens of crassicornis bearing cotype labels in the 
collections of the M.C.Z. and the A.M.N.H. These specimens were 
taken at Belmont, North Carolina, hence they are certainly not co- 
types. They may be a part of the series on which Forel based his 1901 
description of crassicornis. 

It has been necessary to alter the status of several of the variants 
which Wheeler assigned to this species. His subspecies vallicola and 
porcula have both been treated as separate species. It may be recalled 
that, because of its very distinct structural features, Wheeler was 
doubtful that porcula belonged to crassicornis. The distribution of 
porcula and its behavior in the field both indicate that this insect 
behaves as a species. The reasons for these changes have been pre- 
sented under the species involved. I am also unable to see why 
Wheeler treated teira as an intergrade between porcula and crassicornis. 
Actually tetra is a western subspecies of crassicornis and WTieeler's 
variety diversipilosa is the intergrade which connects tetra with the 
typical eastern crassicornis. For this reason tetra has been given sub- 
specific rank and diversipilosa has been thrown into the synonymy of 
crassicornis. Since a good deal has been said about the lack of erect 
hairs on the gaster of the typical crassicornis, it seems well to note 
that this is not always the case. Even when erect hairs are present, 
however, they are notably less abundant than those of the western 
race tetra, hence this difference can still be used as a means for sepa- 
rating the two insects. 

19. PHEIDOLE CRASSICORNIS TETRA Wheeler 

Ph. crassicornis subsp. porcula var. tetra Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 24, p. 467 (1908) 9 01. 

Type loc: Austin, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: central Texas to southern Arizona. 

It is difficult to see why Wheeler assigned tetra to porcula, for the 
two have little in common. The scape of tetra is like that of crassicornis 
and tetra should have been assigned to crassicornis at the start. 



20. PHEIDOLE DAVISI Wheeler 

Ph. davisi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 380 (1905) 9 91. 
Type loc: Lakehurst, New Jersey. Types: A.M.N.H., M.C.Z. 



CREIGHTON: ANTS OF NOKTH AMERICA .1.. 

Range: southern New Jersey to northern Alabama. In the southern part of 
the range davisi occurs in the valleys of the Appalachian Highlands. 



21. PHEIDOLE DENTATA Mayr 

After studying a large amount of material belonging to dentata and 
commutata, the writer finds himself in agreement with those myrme- 
cologists who have refused to accept Emery's unsupported statement 
that commutata is a separate species. This vexing difference of opinion 
need never have arisen. Half a century ago Forel presented good 
evidence to show that dentata and commutata cannot be regarded as 
separate species. It is significant that Forel's conclusion was based 
on a field acquaintance with this insect. In 1900 Forel visited North 
Carolina, where he had the opportunity to study dentata and to observe 
the variability which this species exhibits. Forel's opinion in this 
matter should have carried more weight than those of his European 
contemporaries, who knew dentata only from cabinet specimens. This 
was not the case. While Emery agreed with Forel that dentata should 
be removed from morrisi and given specific rank, he would not agree 
to including commutata with dentata. As far as the writer has been 
able to determine, Emery never presented any reason why he regarded 
commutata as a separate species. This is entirely out of character 
with Emery's usual caution. It is not surprising that most American 
myrmecologists have refused to accede to Emery's treatment of com- 
mutata. There is abundant evidence that Forel was correct in re- 
garding dentata and commutata as representatives of the same species. 
There is no lack of material belonging to dentata for the insect is one 
of the most abundant species of Pheidole in the southeastern United 
States. A very large number of specimens of dentata can now be 
examined in American collections and a study of these will show that 
Forel's view is far sounder than the stand advocated by Emery. In 
my opinion, the only trouble with Forel's treatment is that he did not 
carry his revisionary work far enough. There is no justification for 
the recognition of commutata or faisonsica, both of which are based on 
unstable characters. Over its entire range dentata produces variations 
in color and the length of the epinotal spines. Not only are these 
variations entirely devoid of geographical significance but they are so 
frequently encountered that it is impossible to regard them even as 
nest varieties. In most nest series of dentata there will be specimens 
referable to commutata or faisonsica. What must be realized is that in 
dentata both color and spine length are too variable to be used as 
satisfactory criteria for infraspecific delimitation. There follows the 
synonymy of Ph. dentata Mayr- 



l/. BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Ph. marrisi var. dentata Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 457 

(1886) 9 Old". 

Ph. dentata Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 351 (1901) 9 21 c?. 
Ph. dentata var. faisonsica Forel, Ibidem, p. 352 (1901) 9 01. 
Ph. commutata Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 459 (1886) 9 21 ; 

Mayr, Ibidem, Vol. 37, p. 598 (1887); Emery, Zool. Jahrb. Syst., Vol. 8, 

p. 289 (1895) 9 01. 
Leptothorax tennesseensis Cole, Amer. Mid. Naturalist, Vol. 19, p. 238 (1938) 9 ; 

Cole, Proc. Ent. Soc. Wash., Vol. 50, No. 4, p. 82 (1948) (synonymic note). 
Type loc: Florida. Types: none in this country. 
Range: North Carolina to Florida and westward through Tennessee and the 

Gulf States to eastern Texas. 

I have used the presence of epinotal spines to separate dentata from 
morrisi in the key, since this is the most convenient difference for 
keying. Even though the length of the epinotal spines is variable in 
dentata, there is nothing to indicate that the epinotum is ever unarmed. 
Conversely, the epinotum of morrisi never bears spines, hence there is 
little likelihood of confusing the two species if epinotal armature is 
used as a separatory character. The other differences which distinguish 
dentata from morrisi are matters of proportion which are difficult to 
express in a key. 

Forel was of the opinion (1901) that dentata always nests in old logs 
and never constructs nests in the soil surmounted by masonry domes. 
This statement is in need of considerable modification. It is true that 
dentata often nests in rotten logs and old stumps and, under such 
circumstances, it does not construct a mound of excavated soil above 
the nest. But dentata also nests in soil and when it does the nest 
usually has a mound of excavated earth above it. As has been noted 
elsewhere this flexibility of nesting habits is unusual in a species of 
Pheidole, for most members of this genus nest only in soil. 



22. PHEIDOLE DENTIGULA M. R. Smith 

Ph. dentigvla M. R. Smith, Ent. News, Vol. 38, p. 310 (1927) 9 91; M. R. 

Smith, Ibidem, Vol. 39, p. 245 (1928) 9 . 

Type loc: A & M College, Mississippi. Types: Coll. M. R. Smith. 
Range: Tennessee southward through Alabama and Mississippi. The insect 

apparently does not occur to the east of the Appalachian Highlands. 



23. PHEIDOLE DESERTORUM Wheeler 

Ph. desertorum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 22, p. 337 

(1906) 9 21 9 cf. 
Ph. desertorum var. comanche Wheeler, Ibidem, p. 339 (1906) 9 21 . 



CEEIGHTON: ANTS OF NORTH AMERICA 1/y 

Ph. desertorum var. maricopa Wheeler, Ibidem, p. 339 (1906) 9 <4. 

Type loc: Ft. Davis, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 

Range: western Texas to Arizona. 

The two color varieties, comanche and maricopa, which Wheeler 
established when he first described desertorum, should not, in my 
opinion, be recognized as valid forms. When maricopa was first de- 
scribed there might have been reason to believe that this form is a 
light colored western race of desertorum. At that time the range of 
maricopa, which was described from the Grand Canyon of Arizona, 
seemed to lie well to the west of those of the typical desertorum and 
comanche. As more material has come into collections the ranges of 
all three forms have tended more and more to become coincidental. 
The only difference appears to be that the pale forms, referable to 
maricopa, are more abundant in the western half of the range of 
desertorum than in~the eastern half . The dark form, comanche, seems 
about equally abundant throughout. Hence over most of the range of 
desertorum all three color forms may exist in close proximity. Whatever 
these color variants are, they are not geographical races. I can see no 
reason why they merit formal names and have synonymized both with 
the typical desertorum. 



24. PHEIDOLE FLORIDANA Emery 

Ph. flavens subsp. floridana Emery, Zool. Jahrb. Syst., Vol. 8, p. 293 

(1895) 9 21 9 . 

Type loc: Cocoanut Grove, Florida. Types: A.M.N.H., M.C.Z. 
Range: known only from Florida, where it is by no means abundant. 



25. PHEIDOLE FLORIDANA LAUTA Wheeler 

Ph. lauta Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 470 (1908) 9 -21 9 cf. 
Type loc: Comal River, New Braunfels, Texas. Types: A.M.N.H., M.C.Z., 

Coll. W. S. Creighton. 
Range: central Texas to Alabama. 

The structural differences which separate lauta from floridana are 
very slight and consist mainly of a narrower and differently shaped 
head in the minor worker of the latter insect. There is no longer a 
wide gap separating the range of lauta from that of floridana. I have 
taken lauta in Alabama and I am reasonably certain that the record 
which Dr. M. R. Smith published for specimens of floridana taken at 
Ocean City, Mississippi also refers to this insect. There is no reason 



iou BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

why, at present, lauta may not be regarded as a western race of 
floridana. It will not be surprising if further study proves the two 
insects to be too closely related to permit even subspecific separation. 

26. PHEIDOLE GRALLIPES Wheeler 

Ph. grallipes Wheeler, Psyche, Vol. 23, p. 40 (1916) (rumen nov.). 

Ph. susannae subsp. longipes Pergande, Proc. Calif. Acad. Sci. (2), Vol. 5, 

p. 885 (1895) V 01 (nee F. Smith). 
Ph. longipes, Forel, Biol. Centrali. Amer. Hym., Vol. 3, p. 65 (1899); Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 397 (1915) 9 . 
Type loc: Sierra San Lazaro, Mexico. Types: TJ.S.N.M. 
Range: coastal region of southern California south into Lower California. 

Although Mallis (1941) has reported a record for grallipes from Los 
Angeles County, all the other records for this species come from the 
San Diego area. The insect seems to do little more than barely get 
over the border into California and Mr. Mallis' record must certainly 
lie at the northern limit of the range. 



27. PHEIDOLE HUMERALIS Wheeler 

Ph. humeralis Wheeler, Bull. Amer. Mus. Nat, Hist., Vol. 24, p. 456, pi. 27, 

fig. 39 (1908) 9 21. 

Type loc: Corsicana, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



28. PHEIDOLE HYATTI Emery 

Ph. hyatti Emery, Zool. Jahrb. Syst., Vol. 8, p. 295 (1895) 9 01; Wheeler, Bull. 

Amer. Mus. Nat. Hist,, Vol. 24, p. 456, pi. 27, fig. 32 (1908) 9 21 9 <?; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 558, pi. 7, fig. 26 

(1947) Qt. 
Ph. hyatti var. ecilonodora Wheeler, Bull. Amer. Mus. Nat, Hist., Vol. 24, 

p. 463 (1908) 9 01. 

Type loc: San Jacinto, California. Types: A.M.N.H. 
Range : western Texas through southern New Mexico and Arizona to southern 

California. 

The variety ecitinodora is so clearly a synonym of the typical form 
that it would seem scarcely worth mentioning were it not for one 
remarkable feature. Although ecitinodora is usually considered a color 
variety, it would seem to have actually been an odor variety. Wheeler 
believed that the soldiers of ecitonodora possess the 'rank fecal odor of 



CREIGHTON: ANTS OF NORTH AMERICA 181 

Eciton workers'. Wheeler may not have intended to imply that this 
form is primarily distinguished by odor but his choice of the name 
ecitonodora is hard to explain on any other basis. There is no significant 
color difference between ecitonodora and the insect which Wheeler re- 
garded as the 'typical' hyatti. The color of hyatti varies considerably 
and the amount of variation in some nest series is greater than in 
others. What Wheeler did was to attribute the colonies with more 
constant color to the typical hyatti (hence his supposition that this 
form is rare) while the ordinary variable color pattern became the 
'common form', the variety ecitonodora. 

29. PHEIDOLE HYATTI SOLITANEA Wheeler 

Ph. hyatti subsp. solitanea Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 409 (1915) 9 21 9 . 

Type loc: Point Loma, San Diego, California. Types: M.C.Z., A.M.N.H. 
Range: the coastal area in the San Diego region of California and probably 

south into Lower California. 

The status of solitanea is at present problematical and will probably 
remain so until we know more of the ant fauna of Lower California. 
This subspecies differs from the typical hyatti mainly in having a 
smaller size in all three castes. The typical form often produces nests 
in which the majors are smaller than average but in such nests the 
sexual forms are of normal size. It happens that the present records 
for solitanea come from an area in which hyatti is also present. But 
it is possible that solitanea ranges south into Lower California and that 
the typical hyatti does not occur there. There are records of hyatti 
from Lower California but these seem to have been based on workers. 
It is, therefore, quite possible that these records should actually apply 
to solitanea. 



30. PHEIDOLE KINGI INSTABILIS Emery 

Ph. kingi subsp. instabilis Emery, Bull. Soc. Ent. Fr., p. 120 (1901) 9 01; 
Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 2, pi. 1, fig. 1-9 
(1907) 9 21 9 <7; Wheeler, Ibidem, Vol. 24, p. 431 (1908) 9 2i 9 cf; 
Wheeler, Ants, Columbia Univ. Press, p. 89, fig. 52 a-g (1910) 9 21 9 cf. 

Type loc: Austin, Texas. Types: M.C.Z., Coll. W. S. Creighton. 

Range: central Texas west to the Rio Grande and south into Mexico. 

Ph. kingi possesses a strongly polymorphic worker caste. This fact 
was used by Forel as the basis for the establishment of the subgenus 
Allopheidole. Using kingi as the subgenotype, Forel built up a very 



lew BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

heterogeneous group in which the only common feature was the poly 
morphism of the worker. Wheeler attempted to better the matter by 
establishing another subgenus, Cardiopheidole, for vasliti and its vari- 
ants. The only reason for the existence of Cardiopheidole is the fact 
that vasliti is not closely related to kingi. On this basis it would be 
necessary to establish a separate subgenus for each of the species 
which Forel placed in Allopheidole. Emery was clearly aware of the 
difficulties in which Forel and Wheeler had become embroiled and 
threw over both subgenera without hesitation. Emery's view is the 
only acceptable one for all the evidence indicates that polymorphism 
in the worker caste of Pheidole is not an index of subgeneric relation- 
ship but a trait that may appear in wholly unrelated species. 



31. PHEIDOLE KINGI TOKPESCENS Wheeler 

Ph. kingi subsp. torpescens Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 404 (1915) V 01. 
Type loc: Carnegie Desert Laboratory (near Tucson), Arizona. Types: 

M.C.Z. 
Range: known only from type material. 



32. PHEIDOLE LAMIA Wheeler 

Ph. lamia Wheeler, Amer. Naturalist, Vol. 35, p. 534, fig. 11 (1901) 9 01; 

Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 477, pi. 26, figs. 14-17 

(1908) 9 01. 

Type loo: Austin, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



33. PHEIDOLE MACCLENDONI WTieeler 

Ph. macclendoni Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 450, pi. 27, 

fig. 36 (1908) 9 01. 
Type loc: Laredo and Corsicana, Texas. Types: A.M.N.H., M.C.Z., Coll. 

W. S. Creighton. 
Range: southern Texas to Arizona. 



34. PHEIDOLE MAKCIDULA WTieeler 

Ph. marddula Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 457(1908) 9 01. 
Type loc: Barton Creek, Austin, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



CREIGHTON: ANTS OF NORTH AMERICA iocs 

35. PHEIDOLE METALLESCENS Emery 

Ph. metallescens Emery, Zool. Jahrb. Syst., Vol. 8, p. 294 (1895) 9 . 
Type loc: St. George, Florida. Types: none in this country. 
Range: Gulf States, Florida to Texas. 

The distinguishing feature of the typical form is the rather evenly 
sculptured head of the minor worker. This character is very constant 
in specimens coming from the eastern part of the range. The violaceous 
reflections in the minor worker are much less pronounced than those 
of the subspecies splendidula and some specimens show very little color. 



36. PHEIDOLE METALLESCENS SPLENDIDULA Wheeler 

Ph. metallescens subsp. splendidula Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 24, p. 474, pi. 26, figs. 20, 21 (1908) 9 21 9 cf . 

Typeloc: DelRio, Texas (by present restriction). Types: A.M.N.H., M.C.Z. 
Range: southwestern Texas. 

It appears imperative to restrict the type material of splendidula 
to those specimens from the southwestern part of the state. Much of 
the material which Wheeler used in the original description of this 
subspecies is plainly transitional to the typical form. This might have 
been expected, since some of the type series came from points as far 
east as Denton, Texas. It may be recalled that Wheeler commented 
on the variation in the type material of splendidula, which is not 
surprising for he was dealing, in part, with intergrades. The major 
range of splendidula probably lies in northeastern Mexico. In its 
typical form splendidula is easily distinguished from the eastern 
metallescens by the smooth and shining head of the minor worker. 
The violaceous reflections in this caste are also much more pronounced. 



37. PHEIDOLE MILITICIDA Wheeler 

Ph. militicida Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 398(1915) 9 21. 
Type loc: Hereford and Benson, Arizona. Types: A.M.N.H., M.C.Z., Coll. 

W. S. Creighton. 
Range: known only from southern Arizona. 



38. PHEIDOLE MOHHISI Forel 

Ph. morrisi Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R. p. 46 (1886) 9 21 ; Mayr, 
Verb. Zool-bot. Ges. Wien, Vol. 37, p. 568 (1887) 9 21; Forel, Ann. Soc. 
Ent. Belg., Vol. 45, p. 350 (1901) 9 21 9 d". 

Ph. morrisi var. vancae Forel, Ibidem, p. 351 (1901) 9 Qt 9 cf. 

Type loc: Vineland, New Jersey. Types: none in this country. 

Range: southern New Jersey south to Florida and the eastern Gulf States. 



184 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

It is impossible to recognize the validity of Forel's variety vancae 
because of the variability of the definitive characters on which that 
form was based. The principal differences are those of size and color 
and in neither case is the difference great. It is impossible to correlate 
such distinctions with distribution for morrisi shows such fluctuations 
over its entire range. In addition to the lack of spines on the epinotum, 
morrisi may be distinguished from dcntata by its slightly longer an- 
tennal scapes and the more convex sides of the head in the major. 
The postpetiole of morrisi is less transverse than that of dentata. 

39. PHEIDOLE MORRISI IMPEXA Wheeler 

Ph. morrisi var. impexa Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 461, 

pi. 27, fig. 31 (1908) 9 01 9 d\ 

Type loc: Del Valle, Austin, Texas. Types: A.M.N.H., M.C.Z. 
Range: Texas and Oklahoma. 

Wheeler regarded impexa as no more than a variety but it should 
be considered as a western race of morrisi. The insect is larger than 
the typical eastern form and has a much more abundant abdominal 
pilosity. The two forms will probably be found to intergrade in eastern 
Texas and Louisiana. 



40. PHEIDOLE NUCULICEPS Wheeler 

Ph. nuculiceps Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 473(1908) 9 21 
Type loc: Comal River, New Braunfels, Texas. Types: M.C.Z. 
Range: known only from type material. 



41. PHEIDOLE PILIFERA (Roger) 

The revisionary changes proposed for the pilifera complex are rather 
extensive and it seems preferable to consider all of them in a single 
account. In the present volume this group of variants has been 
treated as follows: 

Ph. pilifera Roger 

= var. simulans Wheeler 
= subsp. septentrionalis Wheeler 
subsp. artemisia Cole 
subsp. coloradensis Emery 

= var. neomexicana Wheeler 
subsp. pacifica Wheeler 



CREIGHTON: ANTS OF NORTH AMERICA loo 

The outstanding change is the inclusion of the subspecies pacifica, 
which has hitherto been related to xerophila. In my opinion, pacifica 
has much more in common with pilifera than with xerophila. The 
major worker of pacifica has strongly developed humeral angles, 
transverse striae on the occiput and a sharp crest on the petiolar node, 
all of which characters are present in pilifera but not in xerophila. 
The minor worker of pacifica is extensively sculptured, as in pilifera, 
and not smooth like the worker of xerophila. To these structural simi- 
larities may be added the fact that pacifica occurs in an area that 
cannot be considered exceptionally arid. In this respect it resembles 
pilifera rather than xerophila. 

The remaining changes have to do with synonymy. In 1908 Wheeler 
presented a careful redescription of Emery's variety coloradensis. 
Wheeler pointed out the notable structural differences which separate 
this insect from the typical pilifera and proposed subspecific status for 
coloradensis. This proposal is entirely satisfactory but certain corol- 
laries which accompanied it are not. At this same time Wheeler gave 
varietal status to a form which he called simulans and subspecific 
status to another, which he called septentrionalis. Wheeler contended 
that simulans is transitional in sculpture between the typical pilifera 
and the subspecies coloradensis. There is no reason why intergrading 
forms of this sort should not occur but the range of the material on 
which simulans was based removes any possibility that this insect is 
an intergrade between pilifera and coloradensis. All material belonging 
to simulans came from southern New York and New Jersey. The 
major portion of the range of pilifera lies to the west of this area and 
meets that of coloradensis in the prairie states. It seems absurd to 
contend that simulans is transitional between pilifera and coloradensis. 
The last place where one would look for such intergrades is along the 
Atlantic Seaboard. In the opinion of the writer simulans has nothing 
to do with coloradensis and represents one of the minor fluctuations 
of sculpture which occur in the eastern population of pilifera. The 
subspecies septentrionalis is equally suspect. There is little need to 
consider the sculptural distinctions cited by Wheeler for this sub- 
species, for they come within the range of variation shown by the 
typical pilifera. But Wheeler's statement that the head of septentri- 
onalis is 'much shorter' than that of pilifera needs revision. Since I 
could see no obvious difference in the shape of the head in the two 
forms I made micrometer measurements of the heads of the major 
workers in the long series of cotypes on which septentrionalis was 
established. The heads of these specimens measure 1.6 mm. from the 
clypeal border to the top of the occipital lobes. The greatest width of 
the head is 1 .5 mm. This supports Wheeler's contention that the head 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



of the major of septentrionalis is not much longer than broad, but it 
does not distinguish that form from the typical pilifera. Many of the 
specimens which Wheeler identified as the typical pilifera agree exactly 
with the measurements given above and, in those instances where the 
head of the major is larger, the same proportions hold. In my opinion 
septentrionalis cannot be defended, even as a nest variety. Its de- 
scription seems due to a mistaken conviction that variation in size 
cannot occur in the major worker of the typical pilifera. In conclusion 
it may be added that the coexistence of septentrionalis and the typical 
pilifera in the same stations in the east shows that the former insect 
is not a subspecies. 

The status of the variety neomexicana is better from a distributional 
standpoint, but it will not stand up to the definitive structural char- 
acters which are supposed to distinguish it. This variety was differ- 
entiated by its heavier sculpture, particularly that on the occipital 
lobes of the major, where transverse rugules occurred. These rugules 
were, supposedly, absent in the subspecies coloradensis. An exami- 
nation of the type series of both variants has shown that each series 
contains both smooth and rugose individuals. Moreover, the writer 
has never seen a nest series in which both types of individuals did not 
occur. There seems to be no possibility that this variation can be 
explained on the basis of intergradation between two races. Since 
these fluctuations are shown by the entire population of pilifera which 
occurs in the southern Rockies, it must be assumed that this variability 
is inherent in the subspecies coloradensis, an assumption which is 
entirely in keeping with the comparable variability of the typical 
pilifera. 

Cole's subspecies artemisia is known mainly from the type series, 
hence it is impossible to state how this form behaves. The types of 
artemisia are quite distinct from those of coloradensis and this same 
distinction applies to range. There is no reason, at present, to doubt 
the validity of artemisia as a Great Basin race of pilifera. There follows 
the synonymy of Ph. pilifera Roger: 

Leptothorax pilifer Roger, Berl. Ent. Zeitschr., Vol. 7, p. 180 (1863) 9 . 

Ph. pilifera Emery, Zool. Jahrb. Syst., Vol. 8, p. 290 (1895) 9 21. 

Ph. pilifera var. simtdans Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 
p. 436 (1908) 9 21. 

Ph. pilifera subsp. septentrionalis Wheeler, Ibidem, p. 436 (1908) 9 21. 

Ph. pennsylvanica Roger, Berl. Ent. Zeitschr., Vol. 7, p. 199 (1863) 21; Mayr, 
Verh. Zool-bot. Ges. Wien, Vol. 20, p. 981 (1870); Mayr, Ibidem, Vol. 36, 
p. 455 (1886) 9 21 9 <f ; Mayr, Ibidem, Vol. 37, p. 588 (1877) 9 21. 

Type loc: Pennsylvania. Types: none in this country. 

Range: Massachusetts to North Carolina and west to Iowa and Nebraska. 



CREIGHTON: ANTS OF NORTH AMERICA 18 

42. PHEIDOLE PILIFERA ARTEMISIA Cole 

Ph. pilifera subsp. artemisia Cole, Ann. Ent. Soc. Amer., Vol. 26, No. 4, p. 616 
(1933) 9 01; Cole, Amer. Mid. Naturalist, Vol. 20, No. 2, p. 372 (1938) 9 . 

Type loc: Provo, Utah. Types: Coll. A. C. Cole, Coll. C. H. Kennedy, Coll. 
W. S. Creighton. 

Range: known only from Utah. 

43. PHEIDOLE PILIFERA COLORADENSIS Emery 

Ph. pilifera var. coloradensis Emery, Zool. Jahrb. Syst., Vol. 8, p. 290 

(1895) 9 01. 
Ph. pilifera subsp. coloradensis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 434 (1908) 9 01 9 <?. 
Ph. pilifera subsp. coloradensis var. neomexicana Wheeler, Ibidem, p. 436 

(1908) 9 01. 
Type loc: West Cliff and Pueblo, Colorado. Types: A.M.N.H., M.C.Z., 

Coll. W. S. Creighton. 
Range: northern New Mexico through Colorado to the Dakotas. 

This insect prefers to nest in canyon bottoms and along the banks 
of streams. In Colorado it is most frequently encountered at elevations 
between 5000 and 6000 feet. It is more abundant on the eastern slopes 
of the Rockies than to the west of them. The colonies are generally 
larger than those of the typical eastern pilifera. 

44. PHEIDOLE PILIFERA PACIFICA Wheeler 

Ph. xerophila subsp. pacifica Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 404 (1915) 9 01 9 cf. 
Type loc: Pasadena and Lakeside, California. Types: A.M.N.H., M.C.Z., 

Coll. W. S. Creighton. 
Range: known only from type material. 

45. PHEIDOLE PINEALIS Wheeler 

Ph. pinealis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 459, pi. 27, 

fig. 38 (1908) 9 01. 

Type loc: Limpio Canyon, Ft. Davis, Texas. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



46. PHEIDOLE PORCULA Wheeler 

Ph. crassicornis subsp. porcula Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 466, pi. 27, fig. 35 (1908) 9 01. 

Type loc: Chisos Mountains, Texas. Types: A.M.N.H., M.C.Z. 
Range: mountains in the Big Bend area in Texas north to Colorado. This 

insect undoubtedly occurs in the highlands of Chihuahua. 



loo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

It may be recalled that Wheeler treated porcula as a subspecies 
rather than as a species because he felt that his variety tetra linked 
porcula to the typical crassicornis. There is little to support this view. 
As has been shown elsewhere, tetra is a western race of crassicornis. 
It intergrades with crassicornis but does not do so with porcula, 
although the range of porcula is coincidental with that of tetra over 
a large area in western Texas. It seems best, therefore, to regard 
porcula as specifically distinct from crassicornis. While the striking 
lateral expansion at the base of the antennal scape of the major is the 
outstanding characteristic of porcula, there are other differences which 
separate this insect from crassicornis. As Wheeler noted, porcula is 
larger, less hairy and more heavily sculptured than crassicornis. Its 
minor worker has the epinotum armed with denticles instead of the 
spines which are present in the minor of crassicornis. 

47. PHEIDOLE PEOSEEPINA Wheeler 

Ph. proserpina Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 437 

(1908) 9 21. 

Type loc: Gila River, Tempe, Arizona. Types: A.M.N.H., M.C.Z. 
Range: deserts of southern Arizona. 



48. PHEIDOLE EIDICULA Wheeler 

Ph. ridicula Wheeler, Proc.New Eng. Zool. Club, Vol. 6, p. 29, figs. 1, a, b. 

(1916) 21. 

Type loo: Brownsville, Texas. Types: M.C.Z. 
Range: known only from type material. 



49. PHEIDOLE SCIOPHILA Wheeler 

Ph. stiophila Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 443, pi. 26, 

figs. 18, 19 (1908) 9 01 9 d". 
Type loc: Austin and New Braunfels, Texas. Types: A.M.N.H., M.C.Z., 

Coll. W. S. Creighton. 
Range: western Texas to southern Arizona. 



50. PHEIDOLE SCIOPHILA SEMILAEVICEPHALA M. R. Smith 

Ph. sdophila subsp. semilaevicephala M. R. Smith, Ann. Ent. Soc Amer., 

Vol. 27, No. 3, p. 385 (1934) 21. 

Type loc: Yuma, Arizona. Types: Coll. M.R. Smith. 
Range: deserts of southern Arizona. 



CREIGHTON: ANTS OF NORTH AMERICA 189 

51. PHEIDOLE SITARCHES Wheeler 

Ph. sitarches Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 440(1908) 9 01 9 . 

Ph. sitarches var. transvarians Wheeler, Ibid., p. 442 (1908) 9 91. 

Typeloc: New Braunfels, Texas (by present restriction). Types: A.M.N.H., 

M.C.Z. 
Range: southern Texas. 

I have restricted the type locality of sitarches to New Braunfels. 
As the following paragraph will show, material coming from the area 
around Austin is not dependable in the case of this species. It is 
unfortunate that Wheeler made extensive use of material coming from 
the Austin region without being aware of the reason for its variability. 
There are three races of sitarches. The typical sitarches is a southern 
race, campestris is a northern and eastern race and the western race 
is represented by the insect which Wheeler described as the species 
soritis. The northern end of the range of the typical sitarches overlaps 
the southwestern end of the range of campestris in the vicinity of 
Austin. In this area of overlap intergrades are produced in abundance. 
Wheeler was aware that the material from Austin varies considerably, 
for he commented on it. But Wheeler did not distinguish between the 
significant characters of the valid subspecies and the inconsequential 
ones of the intergrades. Instead he proposed names for both. His 
variety transvarians and his subspecies rufescens are intergrades. As 
might be expected, the type material of each of the above forms varies 
considerably. Many of the types of rufescens, for example, do not 
differ in any way from those of the typical sitarches. The latter form 
has been saved from a similar variability largely because a part of the 
type series came from New Braunfels. These specimens show a more 
constant structure and Wheeler was able to sort out specimens from 
the Austin area which correspond to them. The whole situation in 
regard to sitarches has been unfortunate. But at least it may serve to 
show the impossibility of analysing infraspecific variation when one is 
forced to deal with a circumscribed population. It is not until one 
leaves the area of intergradation around Austin that the true distri- 
butional characteristics of sitarches can be analysed. 



52. PHEIDOLE SITARCHES CAMPESTRIS Wheeler 

Ph. sitarches subsp. rufescens var. campestris Wheeler, Bull. Amer. Mus. Nat 

Hist., Vol. 24, p. 443 (1908) 9 01. 

Ph. sitarches subsp. rufescetns Wheeler, Ibid., p. 443 (1908) 9 01 9 . 
Typeloc: Henrietta, Texas. Types: A.M.N.H., M.C.Z. 
Range: central Texas northeast to Missouri and east to Mississippi. 



iyu BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

I have chosen to retain the name campestris rather than rufescens 
for the northern race of sitarches. As has already been noted, the type 
series of rufescens is highly variable and does not show clearly those 
characters which distinguish this race. The types of campestris, on the 
other hand, agree well with material coming from a very large region 
which includes northeastern Texas and adjacent states. It is inter- 
esting to note that this population shows no such variation in structure 
as that which is characteristic of the Austin area. A number of records 
which have been attributed to rufescens belong, in my opinion, to 
campestris. Dr. Smith's records of rufescens from Oklahoma and 
Mississippi should be so considered. 



53. PHEIDOLE SITARCHES SORITIS Wheeler 

Ph. soritis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 439 (1908) 9 01. 
Type loo: Albuquerque, New Mexico. Types: A.M.N.H., M.C.Z., Coll. 

W. S. Creighton. 
Range: New Mexico and southern Utah. 

I cannot agree with Wheeler that the node of the petiole in soritis 
differs notably in shape from that of sitarches. In soritis the crest of 
the node is slightly blunter and the impression at the middle of the 
crest is a little deeper but, except for these minor variations, the 
agreement seems remarkably good. I have never seen specimens of 
soritis in which the head of the major was as long as that which occurs 
in some of the soldiers of the typical sitarches. However, since majors 
with short heads also occur in the nests of the typical form, this is 
not a particularly significant difference. 



54. PHEIDOLE SPADONIA Wheeler 

Ph. spadonia Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 400 (1915) 9 01. 
Type loc: Santa Cruz River, Tucson, Arizona. Types: M.C.Z., A.M.N.H., 

Coll. W. S. Creighton. 
Range : known from type material only. 



55. PHEIDOLE TEPICANA CAVIGENIS Wheeler 

Ph. tepicana subsp. cavigenis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 403 (1915) Ot. 

Type loc: Miller Canyon, Huachuca Mountains, Arizona. Types: M.C.Z. 
Range: known from type material only. 



CREIGHTON: ANTS OF NORTH AMERICA iyi 

56. PHEIDOLE TEXANA Wheeler 

Ph. texana Wheeler, Psyche, Vol. 10, p. 97, fig. 4 (1903) 9 01; Wheeler, Bull. 

Amer. Mus. Nat. Hist., Vol. 24, p. 464, pi. 27, figs. 33, 34 (1908) 9 OU 
Type loc: Travis County, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. 

Creighton. 
Range: known from type material only. 



PHEIDOLE TITANIS Wheeler 



Ph. titanis Wheeler, Psyche, Vol. 10, p. 95, fig. 3 (1903) 9 01; Wheeler, Bull. 

Amer. Mus. Nat. Hist., Vol. 24, p. 461, pi. 27, fig. 30 (1908) 9 01. 
Type loc: Paisano Pass, Brewster County and Chisos Mountains, Texas. 

Types: A.M.N.H., M.C.Z. 
Range: western Texas to southern Arizona. 



58. PHEIDOLE TTSONI Forel 

Ph. tysoni Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 349 (1901) 9 21 cT . 
Type loc: Mt. Mitchell, North Carolina. Types: A.M.N.H. 
Range: mountainous areas in western North Carolina, southwestern Virginia 
and eastern Tennessee. 



59. PHEIDOLE VALLICOLA Wheeler 

Ph. crassicornis subsp. vallicola Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 409 (1915) 9 01. 
Type loc: Miller Canyon, Huachuca Mountains, Arizona. Types: M.C.Z., 

Coll. W. S. Creighton. 
Range: mountains of southern Arizona. 

There can be little doubt that vallicola is a separate species and not 
a subspecies of crassicornis. The antennal scapes of vallicola are longer 
than those of crassicornis in both major and minor. The occipital lobes 
of the major of vallicola are finely and densely, granulose in addition 
to the coarse, oval punctures, with their surface subopaque. In crassi- 
cornis these parts are smooth and shining, with the only sculpture 
consisting of the coarse, scattered, oval punctures. The postpetiole of 
the vallicola major is notably less transverse and not much wider than 
the node of the petiole. The head of the minor of vallicola is evenly 
and densely granulose, like the thorax. In crassicornis the head of the 
minor is shining, with a few scattered punctures. Finally both vallicola 
and crassicornis tetra occur together in many parts of southern Arizona 
without showing the slightest indication of intergradation. 



lyz BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

60. PHEIDOLE VASLITI ARIZONICA Santschi 

Ph. arizonica Santschi, Bull. Soc. Ent. Ital., Vol. 41, p. 3 (1909) 91. 

Ph. vasliti subsp. subdentata var. arizonica Wheeler, Jour. N. Y. Ent. Soc., 

Vol. 22, p. 50 (1914) 21. 

Typeloc: Tucson, Arizona. Types: none in this country. 
Range : mountains of southern Arizona. 



61. PHEIDOLE VIRAGO Wheeler 

Ph. virago Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 401 (1915) 9 21. 
Type loc: Santa Cruz River, Tucson, Arizona. Types: M.C.Z., Coll. W. S. 

Creighton. 
Range: known from type material only. 



62. PHEIDOLE XEROPHILA Wheeler 

Ph. xerophila Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 446, pi. 27, 

fig. 37 (1908) 9 210". 

Type loc: Ft. Davis, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: known only from the Davis Mountains of western Texas. 



63. PHEIDOLE XEROPHILA TUCSONICA Wheeler 

Ph. xerophila subsp. tucsonica Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 448 (1908) 9 01. 
Ph. xerophila subsp. tucsonica var. gilvescens Wheeler, Ibidem, p. 448 

(1908) 9 21. 

Typeloc: Tucson, Arizona. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: southern Arizona and the deserts of California. 

Wheeler was of the opinion that gilvescens is an intergrade between 
the typical xerophila and the subspecies tucsonica. It certainly has 
every appearance of being so and it is curious that Wheeler should 
have felt it necessary to name this obviously transitional form. 



Genus EPIPHEIDOLE Wheeler 
(Plate 22, figures 1-3) 

The type material on which this genus was based came from three 
nests which Wheeler found near Colorado Springs. In each nest were 
soldiers and workers of Pheidole pilifera subsp. coloradensis. In addi- 
tion to these, the first nest contained many males of Epipheidole and 



CREIGHTON: ANTS OF NORTH AMERICA iyo 

three males of coloradensis. The second nest contained a single vir- 
gin female of Epipheidole. The third nest contained a fertile (dealated) 
female of Epipheidole and virgin females and males of that genus as 
well. Although Wheeler looked for them, he found no workers of 
Epipheidole. He therefore concluded that Epipheidole is a worker- 
less parasite and that once it has secured entry into the nest of the 
host, coloradensis, the queen of the host species is dispatched by her 
own workers. The second part of this assumption is still problemati- 
cal but it is now clear that Wheeler was not correct in assuming that 
Epipheidole inquilina is a workerless parasite. In 1941 Dr. M. R. 
Smith (foe cit.) announced the discovery of a single worker of this 
species and presented much pertinent data concerning the status of 
Epipheidole. Dr. Smith pointed out that, from a structural stand- 
point, Epipheidole and Pheidole are so closely related that it is im- 
possible to arrive at any satisfactory criteria by which the two may 
be separated. It may be recalled that Emery, who first examined the 
female of Epipheidole, saw nothing inconsistent in treating the in- 
sect as a small queen of coloradensis. Wheeler was aware of this diffi- 
culty when he established Epipheidole but, since he believed it to be 
workerless, he could cite the absence of workers as a feature which 
separated Epipheidole from Pheidole. Now that Dr. Smith has shown 
that Epipheidole possesses workers, it is necessary to reconsider the 
status of this genus. Dr. Smith prefers to continue to recognize Epi- 
pheidole, since he believes that the workers are only rarely produced 
and that the soldier caste is entirely lacking. Since there seems to be 
no way at present of proving or disproving this contention, I have 
concurred with Dr. Smith's view and have retained generic status for 
Epipheidole. It seems certain, however, that we should be prepared 
for the eventual synonymization of Epipheidole with Pheidole. If 
inquilina can produce minor workers there is every reason to suppose 
that it can also produce majors. We may expect these to come to 
light in the future. There would then be no possible justification for 
separating Epipheidole from Pheidole and we would have to regard 
inquilina as a microgynous species in the latter genus. There is con- 
siderable justification for this view whether Epipheidole produces 
major workers or not. From what we know about other parasitic 
genera in the Formicidae, it seems hard to believe that Epipheidole 
would not show some structural features which would distinguish it 
from Pheidole if it were a valid genus. 

For practical purposes the only thing that can be done with Epi- 
pheidole at present is to contrast it with its host, Ph. pilifera colora- 
densis. The male of inquilina is remarkably similar to that of colora- 
densis, from which it differs mainly in its smaller size (3-3.5 mm.). 



194 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The female of inquilina is also small (3-3.3 mm.) and of a peculiar, 
yellowish color. Its postpetiole is suboval, only slightly broader than 
long and with the lateral processes reduced to short angles. The fe- 
male of coloradensis measures 7-8 mm., is dark brown in color and 
has a strongly transverse postpetiole which is much wider than long 
and possesses prominent lateral processes. The worker of inquilina 
differs from that of coloradensis in a number of minor details but pos- 
sesses a clearly marked promesonotal suture which is indistinct or 
lacking in coloradensis. The epinotal spines in inquilina are thick, 
scarcely tapered and bluntly rounded at the tip. Those of colora- 
densis are slender, tapered and sharply pointed. 



1. EPIPHEIDOLE INQUILINA Wheeler 

Epipheidole inquilina Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 15, 
pi. 2, figs. 12-17 (1904) 9 cf; M. R. Smith, Proc. Ent. Soc. Wash., Vol. 
42, No. 5, p. 106, fig. 1 (1940) 9 ; M. R. Smith, Amer. Mid. Naturalist, 
Vol. 37, No. 3, p. 558, pi. 7, fig. 27 (1947) 9 . 

Type loc: female and male, Colorado Springs, Colorado, 
worker, West Point? Nebraska. 

Types: female and male, A.M.N.H., M.C.Z. 
worker, U.S.N.M. 

Range: eastern Colorado to Nebraska. 

Host: Ph. pilifera subsp. coloradensis. 



Genus SYMPHEIDOLE Wheeler 
(Plate 23, figures 1-4) 

Virtually nothing is known about the habits or distribution of this 
genus which is represented by a single species, elecebra. The majority 
of the type series from which Sympheidole was described came from 
a nest taken by Wheeler near Manitou, Colorado. This nest contained 
a single dealated female and eighteen males of Sympheidole as well 
as soldiers and workers of the host, Pheidole ceres. In addition, 
Wheeler had a second female of Sympheidole, also associated with 
workers of ceres, which Schmitt had found near Boulder, Colorado. 
Because he found no female of ceres nor any workers of Sympheidole 
in either of these colonies, Wheeler postulated that Sympheidole is 
a workerless parasite with habits analogous to those of Anergates. 
Wheeler's premise may be correct but there is no way in which it can 
be verified until additional material is secured and the reactions of 
the living insects observed. 



CREIGHTON: ANTS or NORTH AMERICA iyo 

The males and females of Sympheidole are easily distinguished 
from the corresponding castes of the host species. The male of Sym- 
pheidole possesses a rounded and completely unarmed epinotum. The 
postpetiole, when seen from above, is strongly transverse with prom- 
inent, sharp, lateral connules. In the male of Ph. ceres the epinotum 
is strongly angular with the angle often thrown up at either side into 
a blunt projection resembling a very short, obtuse tooth. The post- 
petiole has the lateral connules reduced to low, angular processes. 
The most striking feature of the female of Sympheidole is its smooth 
and shining surface. The sculpture is much less extensive than that 
of the ceres female and on many parts of the body the sculpture con- 
sists only of scattered, piligerous punctures. In addition, the post- 
petiole of the Sympheidole female is almost four times as broad as 
long, with prominent, recurved, lateral projections. The postpetiole 
of the ceres female is proportionatley narrower and lacks the lateral 
processes. 



1. SYMPHEIDOLE ELECEBRA Wheeler 

S. elecebra Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 8, pi. 2, figs. 8-11 
(1904) 90"; Wheeler, Ants, Columbia Univ. Press, p. 497, fig. 277A 
(1910) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 561 
(1947) 9. 

Type loc: Manitou, Colorado. Types: A.M.N.H., M.C.Z. 

Range: eastern Colorado. 

Host: Pheidole ceres. 



Genus CARDIOCONDYLA Emery 

In 1944 Dr. M. R. Smith presented a very thorough study of the 
four species of Cardiocondyla which have been taken in the United 
States. This contribution makes it much easier to handle these spe- 
cies, since it brings together in a single paper data which has pre- 
viously been widely scattered throughout the literature. Dr. Smith 
discussed the distributional peculiarities of Cardiocondyla in some 
detail but he managed to avoid committing himself on the thorny 
problem as to whether any of these species can properly be consid- 
ered as native ants. Since the species belonging to Cardiocondyla 
usually form small colonies and often nest in plant cavities as well as 
in soil, they are easily transported by commerce. A number of the 
species have now been so widely distributed by this meajis that it is 
often difficult to state exactly what region ought to be considered as 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



their native habitat. There would seem to be no doubt, however, 
that the genus is an Old World group. The great majority of the spe- 
cies are known from the warmer portions of Europe, Asia and Africa. 
It is significant that two of the forms known to occur in the United 
States have also been taken in various parts of the world. Since 
both these variants, minutior and bimaculata, belong to species which 
give every indication of having originated in southern Asia, there is 
little reason to suppose that either form is native to this country. 
Much the same considerations apply to emeryi. Although this species 
was originally described from material taken in the Virgin Islands, 
it has since been found to occur widely in Africa and the Malagasy 
region as well as in Asia Minor and India. C. emeryi has produced 
one race in the upper Nile valley and another in Madagascar, a cir- 
cumstance which certainly seems to indicate an African rather than 
an Antillean origin. The writer can see no reason for doubting Emery's 
view that the type series of emeryi came from an area into which the 
insect had been introduced. It must be remembered, however, that 
emeryi occurs widely in the Antilles and it is probably from this region 
that it has been introduced into Florida. Wheeler's species venustula 
presents a much more difficult problem. This species was based on 
material coming from Culebra Island and Puerto Rico. It is also 
known from Mona Island and from Hayti. But aside from these 
Antillean records and a single record from Florida, there seem to be 
no others. It is impossible to relate venustula to any region in the 
Old World on the basis of our present knowledge, and it may be that 
this species has actually originated in the Antilles. It is easier to ac- 
cept this possibility than to believe that venustula is a native of Flor- 
ida. The few native species whose range includes both southern Flor- 
ida and the Antilles invariably occur in Cuba or the Bahamas or both. 
It is not likely that venustula would have a range which skips from 
Puerto Rico and Hayti to southern Florida if the insect were native 
to the latter area. It seems to the writer that it is not only improper 
to regard venustula as a native species but it is highly doubtful if it 
ought to be considered as a member of our ant fauna on any grounds. 
The single record of venustula from Hollywood, Florida is not a proof 
of naturalization. I believe that we should be extremely cautious of 
drawing any conclusions from a single record of this sort. Several of 
our southern ports are subjected to a steady rain of introduced spe- 
cies which are brought in on the banana ships. I have often watched 
these ships unloading at Mobile, Alabama, and I feel quite certain 
that if one cared to do so it would be possible to compile a list of 
'introduced species' for that port which would suggest the ant section 
of the Biologia Centrali Americana. Some of these species manage to 



CREIGHTON: ANTS OF NORTH AMERICA iy/ 

establish themselves in the vicinity of the docks, but they ordinarily 
do not survive the first bout with our winter climate. Records of this 
type of introduction may be of great interest to those concerned with 
pest control, but they seem out of place in a faunal study. However, 
since there is a good chance that venustula may be repeatedly brought 
into Florida and may even manage to establish itself there, I have 
included the species in this work. 

Two features make the recognition of Cardiocondyla an easy mat- 
ter. There is a total lack of erect hairs on all parts of the body and 
the postpetiole of the worker is dorso-ventrally flattened and at least 
twice as wide as the node of the petiole. A similar type of postpetiole 
is found in Solenopsis globularia littoralis but there is little possibility 
for confusion with this species because of the three-jointed antennal 
club and the armed epinotum in Cardiocondyla. In the key which 
follows, the main separatory characters employed are those which 
Dr. Smith presented in his 1944 key. I have, however, considerably 
simplified certain parts of Dr. Smith's key and have taken the liberty 
of presenting the separatory characters in a somewhat different order. 
In my opinion, the thoracic structure of nuda minutior separates it 
rather sharply from the other three species and I believe that it is 
preferable to bring this form out on the first lug of the key rather 
than on the last as was done in Dr. Smith's arrangement. 



Key to the species, of Cardiocondyla 

Dorsum of the thorax, in profile, with the mesoepinotal suture unimpressed 
or at most very feebly impressed; the mesoepinotal suture usually obsolete 

on the thoracic dorsum nuda subsp. minutior 

Dorsum of the thorax, in profile, with the mesoepinotal suture distinctly im- 
pressed; the mesoepinotal suture clearly marked on the thoracic dorsum. .2 
The antennal scapes failing to reach the occipital margin by an amount 
less than the greatest thickness of the scape; epinotum armed with a pair 

of very small denticles which are not spinose venustula 

The antennal scapes failing to reach the occipital margin by an amount at 
least as great as the length of the first funicular joint; epinotum armed with 

a pair of spines 3 

Node of the petiole, seen from above, longer than broad; the anterior border 
of the postpetiole straight or feebly convex when seen from above . . emeryi 
Node of the petiole, seen from above, broader than long; the anterior 

border of the postpetiole distinctly concave when seen from above 

wroughtoni subsp. bimaculata 



19o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

1. CAKDIOCONDYLA EMERYI Forel 
(Introduced) 

C. emeryi Forel, Mitt. Munchen Ent. Ver., Vol. 5, p. 5 (1881) 9 ; E. Andre, 
Ann. Soc. Ent. Fr. (6), Vol. 1, p. 69, pi. 3, figs. 10-12 (1881) 9 cf ; E. Andre, 
Spec. Hym. Europe, Vol. 2, p. 328, pi. 21, figs. 9-12 (1882) 9 cf; Wheeler, 
Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 128, pi. 11, fig. 6 (1908) 9 ; 
Emery, Deutsche Ent. Zeitschr., p. 20, fig. 7 a, b, c (1909) 9 c? (not 9); 
Arnold, Ann. S. Afr. Mus., Vol. 14, p. 200, pi. 5, fig. 5, 7 (1916) 9 9>; 
Emery, Genera Insectorum, Fasc. 174, p. 124, pi. 2, fig. 20 (1922); M. R. 
Smith, Puerto Rico Univ. Jour. Agr., Vol. 20, p. 835, fig. 1 (1930) 9 ; 
Borgmeier, Revist. Ent., Vol. 7, p. 133, figs. 1-5 (1937) <?; M. R. Smith, 
Proc. Ent. Soc. Wash., Vol. 46, No. 2, p. 33, pi. 5, fig. 1 (1944) 9 ; M. R. 
Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 558, pi. 7, fig. 28 (1947) 9 . 

Type loc: St. Thomas, Virgin Islands. Types: none in this country. 

Range: (in the United States) southern Florida. 



2. CARDIOCONDYLA NUDA MINUTIOR Forel 
(Introduced) 

C. nuda var. minutior Forel, Fauna Hawaiensis, Formicid, p. 120 (1899) 9 ; 

M. R. Smith, Proc. Ent. Soc. Wash., Vol. 46, No. 2, p. 38, pi. 5, fig. 3 

(1944) 9. 
Type loc: Honolulu and Molokai Territory, Hawaii. Types: none in this 

country. 
Range: (in the United States) widely distributed in Florida as far north as 

Pensacola. 

The validity of minutior seems strongly suspect. I have a series of 
specimens taken by Prof. E. G. Alexander in northern Siam which 
contains some workers referable to the typical nuda and others that 
are plainly minutior. As the typical form is widely distributed in the 
south Pacific it seems unlikely that minutior can be regarded as an 
Hawaiian endemic. I have given minutior subspecific rank but I 
suspect that further studies on this insect will show it to be a synonym 
of the typical nuda. 



3. CARDIOCONDYLA VENUSTULA Wheeler 
(Introduced) 

C. venustula Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 128, pi. 11, 
fig. 5 (1908) 9 9 ; Wheeler and Mann, Ibidem, Vol. 33, p. 19 (1914) 9 ; 
M. R. Smith, Puerto Rico Univ. Jour. Agr., Vol. 20, p. 836, fig. 2 (1936) 9 ; 



CREIGHTON: ANTS OF NOETH AMERICA 199 

M. R. Smith, Proc. Ent, Soc. Wash., Vol. 46, No. 2, p. 37, pi. 5, fig. 4 

(1944) 9. 
Typeloc: Culebra Island and Coamo Springs, Puerto Rico. Types: M.C.Z., 

A.M.N.H. 
Range: (in the United States) known only from southern Florida. 



4. CAHDIOCONDYLA WEOUGHTONI BIMACULATA Wheeler 
(Introduced) 

C. wroughtoni var. bimaculata Wheeler, Bull. Lab. Zool. Portici, Vol. 24, p. 43 
(1929) 9 9 ; M. R. Smith, Proc. Ent. Soc. Wash., Vol. 46, No. 2, p. 40, 
pi. 5, fig. 2 (1944) 9 . 

Typeloc: Karashisho, Formosa. Types: M.C.Z. 

Range: (in the United States) southern Florida. 

In my opinion bimaculata, obscurior and hawaiensis are all the same 
insect. Wheeler set up the first two varieties on very minor color dif- 
ferences, some of which varied notably in the type series. I entirely 
agree with Dr. Smith that when the types of hawaiensis are better 
known it will probably be necessary to synonymize bimaculata. At 
the same time the form involved appears to be a valid race of wrought- 
oni, hence it may be given subspecific rank regardless of what name 
is applied to it. 



Genus CREMATOGASTER Lund 
(Plate 24, figures 1-^) 

At the present time the North American species of Crematogaster 
are badly in need of revisionary work. The literature which deals 
with this group is scattered, incomplete and often contradictory. 
Any attempt at revision, however, immediately runs afoul of the lack 
of type material in American museums. Not one of the numerous 
North American forms described by European myrmecologists is 
represented by type material in this country. This lack of types forces 
the use of descriptions. The substitution is make-shift at best and it 
is unlikely that a genus as complex as Crematogaster will yield to 
such a method of treatment. Yet, despite this depressing outlook, 
the student of Crematogaster in this country is better situated than 
his European predecessors. He enjoys the advantages of abundant 
material and a first-hand field knowledge of the species with which 
he is dealing. As Arnold has pointed out (1920), the use of field data 
is of paramount importance for evaluating variation in this genus. 



200 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Because of the unusual plasticity of many of the species, any analysis 
based solely on cabinet specimens is apt to lose itself in a maze of in- 
comprehensible details. This is precisely what has occurred in the 
case of the lineolata complex. The species lineolata has been so bur- 
dened with infraspecific forms that it has become unmanageable. 
The studies which have brought about this condition have been 
drawn, in most cases, from small series of cabinet specimens. Emery, 
who is mainly responsible for the construction of the lineolata com- 
plex, lacked adequate field observations which might have led him 
to a more judicious conclusion. There is now good evidence that 
the complex consists of several species. A proposal to break it down 
into five species was made by Wheeler in 1919. As Wheeler's sug- 
gestion was not followed when Emery published the Myrmicine sec- 
tion of the Genera Insectorum in 1921, there has been confusion in re- 
gard to this matter. In the hope of clearing up this misunderstanding 
I have outlined the history of the lineolata complex. 

The foundation for the complex was laid by Emery in 1895. In 
that year the second section of his Beitrage appeared and in that work 
Emery revised the North American representatives of Crematogaster. 
As a result of this revision Fitch's species cerasi and four of Mayr's 
species (clara, coarctata, laeviuscula and opaca) were made forms of 
lineolata. At the same time Emery described five additional variants 
(californica, lutescens, pilosa, mormonum and subopaca) which he as- 
signed to lineolata. Thus in 1895, according to Emery's view, lineolata 
was represented by ten infraspecific forms. The immediately ensuing 
years altered this concept only to provide more variants. In 1908 
Wheeler added a new form, depilis, and reduced Emery's species 
punctulata to varietal status under lineolata. No further change was 
made until 1919, when Wheeler published a list in which lineolata 
was broken down into five species (lineolata, coarctata, lacviuscula, 
opaca and pilosa). Beyond stating that his proposal was "merely a 
return to the position of Mayr", Wheeler gave no reasons for the 
change. This was unfortunate, for it made acceptance largely a mat- 
ter of faith. Had supporting data been presented there would have 
been less likelihood for the erroneous impression that Emery later 
refused to accept Wheeler's stand. It is easy to get this impression 
from Emery's treatment of the lineolata complex in the Genera In- 
sectorum. The fact is that Emery was unaware of Wheeler's sugges- 
tion. The paper which carried Wheeler's revisionary proposal also 
contained the description of a new species, atkinsoni. This species 
is not included in the Genera Insectorum, hence it seems certain that 
Emery had not seen Wheeler's revisionary paper. 

It is necessary to consider the 'survey' of the New World species 



CREIGHTON: ANTS OF NORTH AMERICA 



of the subgenus Acrocoelia which was published under the name of 
Jane Enzmann in 1946. This revision is largely based on Wheeler's 
1919 list but it embodies other changes and includes the Antillean 
and Neotropical representatives of Acrocoelia which Wheeler's list 
omitted. It is somewhat disconcerting to discover that Enzmann 
has made no attempt to present reasons for the revisionary changes 
proposed in this paper. The only evidence which could be adduced 
in this regard would seem to lie in the key which forms a very con- 
siderable part of the publication. There are many highly remarkable 
points about this key. It is prefaced by the following statement : 

"In some cases the original description does not fit the specimens 
studied accurately; the key was therefore made synoptic and was 
based on both, specimens and description." 

If this extraordinary statement is to be taken at its face value it 
must mean that some of the separatory characters in Enzmann's key 
represent a compromise between the original description and speci- 
mens which do not fit that description but which Enzmann, never- 
theless, accepted as representatives of the form in question. Perhaps 
this was actually done in certain cases but what seems more likely is 
that, whenever Enzmann was confronted with this difficulty, the di- 
chotomous arrangement of the key was abandoned and the 'synoptic' 
sections which it. embodies were employed. Since these 'synoptic' 
sections are not given a dichotomous treatment, the forms included in 
them need not be brought out on contrasting characters. As a result, 
forms which are not clearly separable have been given a spurious dis- 
tinction by this peculiar method of treatment. But this is by no 
means the only bad feature of the key. Twenty of its twenty-eight 
dichotomous couplets are so constructed that they can be used only 
if members on both sides of the split are available for comparison. 
The differences cited are of the 'more-less' sort and this practice is 
consistently followed even when there are excellent positive distinc- 
tions available. In addition, far too much reliance has been placed 
upon slight differences of color, a trait which has singularly little 
taxonomic significance in this group. I have found Enzmann's key 
to be largely without value because of the defects mentioned above. 
Perhaps the best indication of its altogether unreliable character is 
the fact that it contains the species kennedyi and creightoni. Both these 
insects are known only from the sexual forms and both are believed to 
be workerless parasites. Hence it is impossible to deal with them suc- 
cessfully in a key which is based on worker characteristics. It seems 
best to regard Enzmann's revisionary proposals as unsupported state- 
ments which do not merit serious consideration. No attempt has been 
made to deal with them in this publication. 



BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 



The situation in regard to the new variants of Acrocoelia described 
by Enzmann is even more depressing. An incredibly inept treatment 
has obscured the authorship, source, specific relationship and struc- 
tural character of the variety called coachellai. It is impossible to de- 
termine from Enzmann's paper what this form is or to be certain of 
where it was taken. The two varieties of lineolata (wheldeni and punc- 
tinodis) which were described as new are probably synonyms of the 
typical lineolata. They have been treated as such in the present work. 

Most of our species of Crematogaster nest under stones, in logs or 
in standing timber, where decay enables them to tunnel in the wood 
or beneath the bark. Many of the species tend aphids and will build 
carton sheds to cover them. Similar carton containers are often made 
by lineolata and used as brood chambers. Such incubators may be 
several yards away from the main nest. I believe that the pendant, 
carton nests of atkinsoni serve the same purpose. In 1919 Wheeler 
expressed the opinion that this habit of atkinsoni was an adaptation 
to a marshy type of habitat which made it impractical for the insect 
to nest in the soil. This theory would be more acceptable if atkinsoni 
always occurred in palustrine areas. According to my observations 
it rarely does so. This ant is abundant in many parts of Alabama. 
It usually nests in soil or logs but, on occasion, it builds pendant, car- 
ton chambers into which the entire colony may move. My observa- 
tions on atkinsoni have been made only during the summer months 
and so I cannot be sure that their residence in the carton is a tem- 
porary one. This is certainly true in the case of lineolata, which aban- 
dons its carton brood chambers at the beginning of the fall. Another 
interesting example of flexibility in nesting habits is found in the case 
of laeviuscula. This insect frequently starts its nests in live-oak galls. 
When the size of the colony has reached a point where there is not 
enough space in the gall, the nest is moved to more spacious quarters 
in a rotten log. 

Before presenting the key to our North American species of Crema- 
togaster, I wish to discuss the status of two species which do not ap- 
pear in the key. These are the supposedly parasitic species kennedyi 
and creightoni. The first species is based upon males and females 
taken in a nest of lineolata. The second was described from females 
which were secured in a nest of pilosa. The most conspicuous charac- 
teristic of both these species is their small size. This and other con- 
siderations led Wheeler to regard them as workerless parasites. This 
supposition may be correct but it should be borne in mind that in each 
case winged females of the "host "species were present. The conclu- 
sion is inescapable that the queen of the "host" species was still pres- 
ent and functional. While her presence does not disprove Wheeler's 



CREIGHTON: ANTS OF NORTH AMERICA 'M6 

contention, it permits another explanation. The small females of 
kennedyi and creightoni may be the "beta forms" of a dimorphic female 
caste. The writer is inclined to favor this view. The structural differ- 
ences which distinguish these small females from the "host" species 
are very slight. Furthermore, the female of creightoni possesses the 
abundant, erect, tibial hairs which are so characteristic of pilosa. It 
is probable that future field observations will make it necessary to 
synonymize kennedyi with lineolata and creightoni with pilosa. 



Key to the species of Crematogaster 

1. Postpetiole suboval and entire, without a trace of a median sulcus (sub- 
genus Orthocrema) 2 

Postpetiole divided by a distinct median sulcus (subgenus Acrocoelia) . . 5 

2. Tip of the antennal scape in repose notably surpassing the occipital border; 

color yellow; the gaster clothed with abundant long hairs 3 

Tip of the antennal scape in repose failing to reach the occipital border; 
color piceous brown; the erect hairs of the gaster short and sparse 

arizonensis 

3. Dorsum of the promesonotum very smooth and shining; rugae, if present, 
feeble and confined to the edge of the pronotum 

minutissima subsp. smithi 

Dorsum of the promesonotum finely punctate in addition to the longi- 
tudinal rugae, the surface feebly shining; rugae well developed and often 
placed toward the center of the promesonotum 4 

4. Epinotal spines about one-half as long as the distance which separates 
their bases and directed upward; pronotum with the rugae usually lateral 

in position minutissima subsp. missouriensis 

Epinotal spines less than half as long as the distance which separates their 
bases and directed more backward than upward; pronotum with two 
prominent rugae near the middle minutissima 

5. Tibiae with numerous completely erect hairs on all surfaces; body hairs 
fine, erect and very abundant, particularly on the gaster where they are 

evenly spaced and form a thin investiture pilosa 

Tibial hairs, when present, appressed over most of the surface, the only 
erect hairs on the tibiae being a small cluster immediately behind the 
spurs; body hairs, when present, never more than moderately abundant; 
erect gastric hairs coarse, widely spaced and not forming an investiture . . 6 

6. Thoracic dorsum without erect hairs or with not more than eight erect 
hairs which are confined to the humeral angles of the pronotum (rarely 
with three or four very short hairs arising from the mesoepinotal suture 

in addition to the hairs at the humeral angles) 10 

Thoracic dorsum with at least fifteen erect hairs which are scattered over 
the entire promesonotum 7 

7. Most of the upper surface of the head covered with distinct, close-set 
punctures, the surface opaque opaca 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



The posterior half of the head moderately to strongly shining, the surface 
smooth, shagreened or moderately punctate but never so densely sculptured 
as to be completely opaque 8 

8. Epinotal spines long and strongly diverging; promesonotum feebly 

sculptured and moderately shining atkinsoni 

Epinotal spines of moderate length, parallel or at most slightly diverging; 
promesonotum heavily sculptured, opaque or subopaque 9 

9. Epinotal spines slightly divergent, their tips suddenly narrowed and often 
deflected outward more strongly than the rest of the spine; color usually 

dirty yellow lineolata subsp. subopaca 

Epinotal spines parallel or nearly so, evenly tapered from base to tip with 
the tips never turned outward; color usually castaneous brown 

lineolata subsp. punctulata 

10. Antennal scape in all sizes of the worker surpassing the occipital border 
by an amount equal to or greater than the length of the first funicular 

joint mormonum 

Antennal scape not surpassing the occipital border or surpassing the 
occipital border by an amount less than the length of the first funicular 
joint (the minims of those species having a worker caste which varies 
strongly in size may have a scape as long as that of mormonum) 11 

11. Epinotal spines very short and suddenly thickened at the base; length not 

exceeding 3 mm., usually less ashmeadi 

Epinotal spines not as above; length usually exceeding 3 mm 12 

12. Size strongly variable (3-5 mm.); head of the largest worker at least 
one-fourth broader than long with the occiput distinctly concave in the 
middle; epinotal spines long and strongly divergent; sculpture feeble; 
head and thorax clear orange yellow, the gaster brown with a yellow patch 

at the base of the first segment laeviuscula 

Not combining all the above characters 13 

13. Dorsum of the thorax completely devoid of erect hairs; promesonotum 
densely punctate, the punctures largely or completely replacing the rugae 
except for a few short ones at the anterior edge of the pronotum .... depilis 
Dorsum of the thorax with at least one long, erect hair at each humeral 
angle; promesonotum not densely punctate or if densely punctate the 
punctures do not obscure the rugae which run completely across the 
promesonotum 14 

14. Thorax with two or three erect hairs at each humeral angle; rugae on the 
dorsum of the promesonotum delicate, the interrugal punctures feeble, the 

surface somewhat shining 15 

Thorax with one long, erect hair at each humeral angle; rugae on the 
dorsum of the promesonotum coarse and vermiculate, the interrugal 
punctures prominent, the surface opaque. . . .coarctata subsp. vermiculata 

15. Posterior half of the head smooth and shining with small, scattered 

punctures or finely shagreened 16 

Posterior half of the head covered with shallow, confluent punctures which 
give it the appearance of being crossed by delicate, longitudinal striae . . 



CREIGHTON: ANTS OF NOKTH AMERICA zOo 

16. Epinotal spines long and divergent with the tips usually bent outward; 
rugae of the promesonotum delicate, scarcely distinct from the interrugal 

sculpture lineolata 

Epinotal spines of moderate length and scarcely divergent, their tips not 

bent outward; rugae of the promesonotum distinct 

lineolata subsp. emeryana 

Subgenus ORTHOCREMA Santschi 

1. CREMATOGASTER (ORTHOCREMA) ARIZONENSIS Wheeler 

Cr. arizonensis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 482, pi. 27, 
fig. 40 (1908) 9 ; Creighton, Psyche, Vol. 46, No. 4, p. 139 (1939) 9 . 

Type loc: Tucson and Phoenix, Arizona. Types: A.M.N.H., M.C.Z. 

Range: mountains of southern Arizona. This species undoubtedly ranges into 
Mexico, although as yet there seem to be no Mexican records for it. 

2. CREMATOGASTER (ORTHOCREMA) MINUTISSIMA Mayr 

Cr. minutissima Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 991 (1870) 9 9 ; 

Creighton, Psyche, Vol. 46, No. 4, p. 139 (1939) 9 . 
Type loc: Texas. Types: none in this country. 
Range: South Carolina to Florida and westward through the Gulf States to 

Texas. 



3. CREMATOGASTER (ORTHOCREMA) MINUTISSIMA SMITHI (new name) 

Cr. (0.) minutissima subsp. thoracica Creighton, Psyche, Vol. 46, No. 4, p. 138 

(1939) 9 (nee Santschi). 

Type loc: Huachuca Mountains, Arizona. Type: M.C.Z. 
Paratypes: Coll. W. S. Creighton. 
Range : known only from the Huachuca Mountains of Arizona. 

Dr. M. R. Smith has recently called my attention to the fact that 
my name thoracica is preoccupied. In 1921 Santschi used this name 
for a form of Crematogaster taken in the Belgian Congo, (Ann. Soc. 
Ent. Belg., Vol. 61, p. 118, 1921). I have, therefore, replaced my 
homonymic name thoracica with the name smithi. 



4. CREMATOGASTER (ORTHOCREMA) MINUTISSIMA MISSOURIENSIS 

Emery 

Cr. victima subsp. missouriensis Emery, Zool. Jahrb. Syst., Vol. 8, p. 288 

(1895) 9. 
Cr. (0.) minutissima subsp. missouriensis Creighton, Psyche, Vol. 46, No. 4, 



/Ub BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

p. 139 (1939) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 558, pi. 7, fig. 29 (1947) 9 . 

Type loc: Missouri. Types: probably none in this country (see below). 
Range: Texas to Missouri. 

In a recent paper I have shown that missouriensis must be regarded 
as a subspecies of minutissima. It was formerly treated as a sub- 
species of the South American mctima. It is unlikely that there are 
any cotypes of missouriensis in this country. Although there are 
specimens so labeled in the M.C.Z. and A.M.N.H. collections, I be- 
lieve that these are a part of the original series retained by Pergande 
and, while authentic, they are probably not cotypes. 



Subgenus ACROCOELIA Mayr 

5. CEEMATOGASTEB (ACROCOELIA) ASHMEADI Mayr 

Cr. ashmeadi Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 463 (1886) 9 <? ; 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 286 (1895) 9 . 
Cr. atkinsoni var. heheola Wheeler, Psyche, Vol. 26, No. 4, p. 110 (1919) 9 cf 

(not the 9). 
Cr. (A.) ashmeadi var. matura Wheeler, Jour. N. Y. Ent. Soc., Vol. 40, p. 8 

(1932) 9. 

Type loc: Florida (by present restriction). Types: none in this country. 
Range: Atlantic Coast States from Virginia to Florida and the eastern Gulf 

States. 

An unfortunate and peculiar mix-up has involved this species with 
the variety helveola. When Wheeler assigned helveola to atkinsoni he 
must have been unaware that the type series of heheola is mixed. 
As far as the workers are concerned both ashmeadi and atkinsoni are 
represented. The male and female which Wheeler described as be- 
longing to heheola actually belong to ashmeadi. I have frequently 
taken both ashmeadi and atkinsoni in Alabama and the sexual forms 
of the two species are too distinct to allow any possibility for mis- 
taking their specific relationships. The female of ashmeadi is (as 
Wheeler noted when he described it as heheola) a small insect mea- 
suring about 6 mm. in length. Its head is as long as broad with the 
sides feebly convex and not notably narrowed in front of the 
eyes. The antennal scapes fail to reach the occipital margin. The 
occipital angles are covered with appressed hairs. In contrast the 
female of atkinsoni measures 8.5-9 mm. in length. Its head is notably 
broader than long and distinctly narrowed in front of the eyes. The 



CREIGHTON: ANTS OF NORTH AMERICA ZOt 

antennal scapes slightly surpass the occipital margin and the occipital 
angles bear numerous, short, erect hairs. It is to be hoped that the 
above explanation will clear up Wheeler's unfortunate error. It is 
regrettable that the circumstance should have confused ashmeadi and 
atkinsoni for the two species are actually very distinct. 

The variety matura, described by Wheeler in 1932, is, in my opinion, 
without validity. This insect was secured in an area where the typical 
form abounds (Miami, Florida). Three of the four characters which 
were given as its diagnostics (color, sculpture and spine length) are 
variable in the typical ashmeadi. Most nests of the typical ashmeadi 
contain some individuals which could be referred to matura. It would 
be difficult to defend this form even as a nest variety. That it repre- 
sents a subspecies is out of the question. I have synonymized matura 
with ashmeadi. 



6. CREMATOGASTER (ACROCOELIA) ATKINSONI Wheeler 

Cr. atkinsoni Wheeler, Psyche, Vol. 26, No. 4, p. 109, fig. 1 b (1919) 9 . 
Cr. atkinsoni var. helveola Wheeler, Ibidem, p. 109 (1919) V (not the 9 cf). 
Type loc: Ft. Myers, Florida. Cotypes: M.C.Z., A.M.N.H., Coll. W. S. 

Creighton. 
Range: Florida, southern Georgia and the eastern Gulf States. A single record 

of this insect from Belmont, N. C. lies well to the north of the main range. 

Wheeler's variety helveola was founded on a mixed type series in 
which the sexual forms and some of the workers are ashmeadi (see 
above). The remaining workers which do belong to atkinsoni are not 
significantly different from the typical form. The only distinction 
which marks them is a lighter coloration. As such pale individuals 
occur in various parts of the range of atkinsoni, it is not possible to 
consider helveola as a subspecies. I have synonymized it with at- 
kinsoni. The nesting habits of atkinsoni have been discussed in the 
introductory paragraphs dealing with the genus Crematogaster. 



7. CREMATOGASTER (ACROCOELIA) COARCTATA Mayr 

Cr. coarctata Mayr, Verh. Zool-bot, Ges. Wien, Vol. 20, p. 990 (1870) 9 . 
Cr. lineolata subsp. coarctata Emery, Zool. Jahrb. Syst., Vol. 8, p. 283 (1895) 9 . 
Cr. lineolata subsp. laeviuscula var. californica Emery, Ibid., p. 285 (1895) 9 . 
Type loc: San Mateo and San Francisco, California. Types: none in this 

country. 
Range: California, San Francisco south to Los Angeles. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



In the present work I have treated vermiculata as a subspecies of 
coarctata. While this interpretation will not cover all the known 
variability in the case of these two insects (see below) it recognizes 
the fact that there is too much intergradation to permit vermiculata 
to have specific status. Both coarctata and vermiculata were described 
from inadequate series (two workers in the case of vermiculata) and 
this has given a false value to the differences which are supposed to 
separate them. The typical coarctata is an easily recognized insect. 
The head is almost completely covered with confluent punctures which 
give the surface a finely striate appearance. The antennal scape dis- 
tinctly surpasses the occipital margin. The pronotum is decidedly 
quadrangular in the larger specimens with the humeral angles well 
marked. The epinotal spines are distinctly divergent. The dorsum 
of the pronotum is feebly shining with the rugae fine and not particu- 
larly wavy and the interrugal punctures weak. The color is piceous 
brown. This is the form which occurs in the north central part of Cal- 
ifornia, particularly in the San Francisco area. It appears to be 
the only representative of the genus which occurs as far north as San 
Francisco. 

The characteristics of the typical vermiculata are quite distinct from 
those of coarctata. In vermiculata the posterior half of the head is 
smooth and shining with the only sculpture consisting of very fine 
punctures. The antennal scape barely surpasses the occipital mar- 
gin. The pronotum is evenly rounded in front. The epinotal spines 
are feebly divergent. The dorsum of the thorax is completely opaque 
and covered with coarse, vermiculate rugae and heavy punctures. 
The head and thorax are orange with the gaster brown. This insect 
has a range which begins in the Los Angeles area and runs eastward 
into Arizona. In the eastern part of this range the structure of ver- 
miculata is quite constant. But in the California coastal area from 
Santa Barbara to San Diego there is a flourishing population of inter- 
grades between vermiculata and the typical coarctata. Emery's vari- 
ety californica is obviously one of these intergrades. But it is not 
possible to explain all the forms which occur in southern California 
on the assumption that they connect coarctata and vermiculata. Some 
of them are more extreme in certain characters than either of the 
above races. I feel sure that the explanation for this lies in the pres- 
ence of a third, unrecognized subspecies in Lower California. When 
this area is better known we may secure the information which is 
needed to clear up the confusing situation which at present marks 
coarctata in southern California. 



CREIGHTON: ANTS OF NORTH AMERICA z(Jy 

8. CREMATOGASTER (ACROCOELIA) COAHCTATA VERMICULATA Emery 

Cr. vermiculata Emery, Zool. Jahrb. Syst., Vol. 8, p. 286 (1895) 9 . 
Type loc: Los Angeles, California. Types: none in this country. 
Range : southern California eastward into Arizona. 



9. CREMATOGASTEH (ACROCOELIA) CREIGHTONI Wheeler 

Cr. (A.) creightoni Wheeler, Psyche, Vol. 40, No. 2, p. 86 (1933) 9 . 

Type loc: Roanoke, Virginia. Types: M.C.Z., A.M.N.H., Coll. W. S. 

Creighton. 
Range : known only from type material. 



10. CREMATOGASTER (ACROCOELIA) DEPILIS Wheeler 

Cr. lineolata subsp. opaca var. depilis Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 24, p. 478 (1908) 9 . 

Type loc: Cerro Carrigal, Mexico. Types: A.M.N.H., M.C.Z. 
Range: southwestern Texas to southern Arizona. This species enters the 

United States at various points along our southern border. Its main 

range lies in Mexico. 

WTieeler was not inclined to attach much significance to depilis, 
which he believed to be an intergrade between punctulata and opaca. 
In my opinion depilis is clearly a separate species and I am unable to 
understand the reason why Wheeler considered it related to either of 
the above forms. It is much less hairy than either of them and the 
cephalic sculpture is also less pronounced. The female of depilis is a 
large insect measuring 9.5-10 mm. It has a head which is notably 
quadrate, slightly broader than long and with the sides not converging 
in front of the eyes. The antennal scapes barely reach the occipital 
margin. The under surface of the head is densely and evenly clothed 
with long, delicate, erect hairs. This insect is distinct from the fe- 
males belonging to the members of the lineolata complex. As the fe- 
male of opaca is unknown, a comparison with that species is at present 
impossible. 



11. CHEMATOGASTER (ACROCOELIA) KENNEDYI Wheeler 

Cr. (A.) kennedyi Wheeler, Psyche, Vol. 37, No. 1, p. 58 (1930) 9 c?. 
Type loc: Robinson Park, Ft. Wayne, Indiana. Types: M.C.Z., A.M.N.H., 

Coll. C. H. Kennedy. 
Range : known only from type material. 



ZIO BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

12. CEEMATOGASTER (ACROCOELIA) LAEVIUSCULA Mayr 

Cr. laeriuscula Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 993 (1870) 9 . 
Cr. lineolata subsp. laeviuscula Emery, Zool. Jahrb. Syst., Vol. 8, p. 284 

(1895) 9 ; Wheeler, Bull. Amer. Mus. Nat. Hist.,Vol. 24, p. 480 (1908) 9 9 . 
Cr. (A.) laeviuscula Wheeler, Psyche, Vol. 24, No. 4, p. Ill (1919). 
Cr. clara Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 993 (1870) 9 . 
Cr. lineolata subsp. laeviuscula var. clara Emery, Zool. Jahrb. Syst., Vol. 8, 

p. 285 (1895); Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 481 (1908). 
Cr. laeviuscula var. clara Wheeler, Psyche, Vol. 24, No. 4, p. Ill (1919); 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 564, pi. 8, fig. 30 

(1947) 9. 

Type loc: Ft. Cobb, Texas. Types: none in this country. 
Range: Oklahoma southwestward through Texas, southern New Mexico and 

Arizona into Mexico. Emery's record of this insect from Indiana is 

certainly erroneous. 

In 1908 Wheeler published data which showed that Mayr's laevius- 
cula is a minim from an incipient nest of clara. Wheeler's evidence 
for this conclusion is incontrovertible. He had taken both forms in 
live-oak galls at various stations in central Texas. Not infrequently 
both forms were found living in different galls on the same tree. 
Wheeler pointed out that the large workers with the characteristics of 
clara were always found in populous colonies, while the small workers 
with the characteristics of laeviuscula invariably came from incipient 
nests. Most significant of all, Wheeler showed that, despite the notable 
size difference of laeviuscula and clara, the sexual forms of the two 
were indistinguishable. There can be no question concerning Wheel- 
er's findings. They may be checked on any large series of workers 
belonging to this species. Minims may not always be present but the 
smaller the workers are, the more closely they approach the conditions 
of laeviuscula. I have two such series of workers taken by Dr. P. J. 
Darlington at Brownsville, Texas. The large workers show all the 
characteristics of clara, the smallest workers those of laeviuscula. It 
is not clear why Wheeler failed to make the synonymy which his ob- 
servations demanded, but it is clear that, under such circumstances, 
the continued use of both names is little short of ridiculous. Since 
laeviuscula has page precedence, the name clara must go into the 
synonymy. 



In the past the species lineolata has been subject to such widely 
different taxonomic treatments that it seems advisable to preface the 
synonymy of this species with a discussion of some of the difficulties 



CREIGHTON: ANTS OF NORTH AMERICA /ll 

which these divergent views have brought about. I have already re- 
ferred, in the introductory paragraphs dealing with the genus Cremato- 
gaster, to the diverse views held by Wheeler and Emery as to the con- 
stitution of lineolata. While I propose to follow WTieeler in splitting 
up the lineolata complex into several species, this is only a partial solu- 
tion to the problem. After all the valid species have been removed 
there still remains a residue of forms which must be dealt with. It is 
these residual forms which I wish to consider in the following para- 
graphs. 

Much of the difficulty connected with the lineolata complex has re- 
sulted from the absence of Say's types. Had these been available for 
examination, Say's rather sketchy original description could have been 
augmented with the details which have since been found necessary. 
These details have been supplied but their accuracy is suspect. For 
subsequent descriptions of the 'typical' lineolata have been based on 
material which Say could not have seen at the time when he 
described lineolata. Say's description may have been brief but it 
was based on specimens taken in Indiana. One would have expected 
that subsequent investigators would have drawn their redescriptions 
of lineolata from material coming from this general region. No doubt 
they would have done so if such specimens had been available but, as 
this was not the case, they used what they had. Thus the two most 
important of these redescriptions (Mayr 1886, Emery 1895) were 
composites based upon material from several areas, none of which 
were anywhere near Indiana. Emery, for example, utilized specimens 
from Virginia and Florida in drawing up his description of the 'typi- 
cal lineolata'. Since the form of this insect which occurs in Indiana 
does not occur in Florida, it seems certain that Emery's association 
was incorrect. 

A second difficulty has to do with Fitch's cerasi. This insect was 
unrecognizable until 1886, at which time Pergande sent named speci- 
mens to Mayr and Emery. As some of Fitch's types are present in 
the collection of the National Museum, it is possible that Pergande 
had compared his specimens with the types of cerasi. Neither Mayr 
nor Emery questioned Pergande 's identification. Mayr contented him- 
self with a brief note to the effect that Pergande's specimens 'belonged 
to lineolata'. Emery was less cautious. He compared cerasi with his 
'typical lineolata', of which he regarded cerasi as a variety, and gave 
differences by which the two could be separated. As has been shown, 
Emery's 'typical lineolata' was almost certainly not the same as Say's 
insect. Thus Emery's comparison meant little, since he had no clear 
concept of the nature of the typical form. Yet this comparison has 
been the basis for the subsequent recognition of cerasi which, on 



/!/ BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Emery's statement, is held to be a pale variety of lineolata. This state- 
ment has been reversed to make the typical lineolata a dark-colored 
insect, a view which can scarcely be supported by field observations. 

The examination of a very large amount of material coming from 
the northeastern United States has convinced the writer that color 
distinctions are without taxonomic significance in the case of lineolata. 
It is only in the extreme western portion of its range that the typical 
lineolata appears to show any notable constancy in this respect. The 
western specimens appear to be uniformly pale, but over most of its 
range lineolata shows wide variations in color. It is certain that these 
color fluctuations have no geographical connection. They occur at 
random and not infrequently appear in closely adjacent nests in the 
same area. There is good indication that they represent a response to 
local environmental conditions such as temperature and moisture. 
For this reason Emery's attempt to attach names to these color vari- 
ants seems to have been ill-advised. 

While the varieties cerasi and lutescens cannot be regarded as geo- 
graphical races, there are other variants related to lineolata which 
can. It may simplify what follows to outline the range of the typical 
lineolata, since it is more extensive than that of any of the other sub- 
species. The range of the typical lineolata begins in southern New 
Brunswick and runs southwestward through New England, southern 
Ontario and the North Central States. It ultimately reaches eastern 
Colorado, but the insect is decidedly rare in that region. In the east 
the main range of the typical lineolata apparently terminates at about 
the latitude of Virginia, but there are extensions which run south- 
wards at higher elevations in the Appalachian Highlands as far as 
northern Georgia. The subspecies subopaca has a range which overlaps 
that of the typical form in a large area extending from southern New 
England south to Virginia and west in the region which lies immedi- 
ately to the south of the Great Lakes. In this area of overlap many 
intergrades are produced. But the major range of subopaca occurs 
from the South Atlantic States westward to southern Colorado, New 
Mexico and Texas. Over most of this region the only subspecies pres- 
ent is subopaca and in the southern states an elevational difference 
keeps subopaca and the typical lineolata separated, since the former is 
a low-level subspecies. At the western end of its range subopaca 
comes in contact with the subspecies punctulata. Intergrades between 
the two subspecies occur in western Texas, New Mexico, Colorado 
and Kansas. One of these intergrades has been described by Santschi 
as the variety texana. The fourth subspecies belonging to this complex 
has never been named although Emery described it in 1895. It occurs 
at moderate elevations in Colorado, New Mexico and Arizona and 
intergrades with punctulata in the eastern part of New Mexico. 



CREIGHTON: ANTS OF NORTH AMERICA 213 

As a result of the considerations just discussed I would arrange the 
lineolata complex as follows : 

Cr. (A) lineolata (Say) 

= var. cerasi Fitch 

= var. lutescens Emery 

= var. punctinodis Enzmann 

= var. wheldeni Enzmann 

subsp. subopaca Emery 

subsp. punctulata Emery 
= var. texana Santschi 

subsp. emeryana (new name) 

There follows the synonymy of Cr. (Acrocoelia) lineolata (Say) : 

Myrmica lineolata Say, Bost. Jour. Nat. Hist., Vol. 1, p. 290 (1836) 9 9 <?. 

Cr. lineolata Roger, Verz. Formicid., p. 37 (1863); Mayr, Verh. Zool-bot. Ges. 
Wien, Vol. 16, p. 901, pi. 20, fig. 11 (1866) V ; Mayr, Ibid., Vol. 20, p. 990 
(1870); Mayr, Ibid, Vol. 36, p. 462 (1886) 9 ; Emery, Zool. Jahrb. Syst., 
Vol. 8, p. 280 (1895) 9 . 

Myrmica cerasi Fitch, Trans. N. Y. State Agri. Soc, Vol. 14, p. 835 (1854) 9 . 

Cr. lineolata var. cerasi Emery, Zool. Jahrb. Syst., Vol. 8, p. 282 (1895) 9 . 

Cr. lineolata var. lutescens Emery, Ibid., Vol. 8, p. 282 (1895). 

Cr. (A.) lineolata subsp. cerasi var. punctinodis Enzmann, Jour. N. Y. Ent. 



Cr. (A.) lineolata subsp. cerasi var. wheldeni Enzmann, Ibid., p. 92 (1946) 9 . 

Type loc: Indiana. Types: none known to exist. 

Range: New Brunswick through New England and the North Atlantic States 
and southwestward through southern Ontario and the North Central 
States to eastern Colorado. A southern extension follows the Appalachian 
Highlands to the latitude of northern Georgia. 

The southern extent of the range of lineolata is something of a prob- 
lem. It has been reported from Florida by several investigators but 
it is doubtful if the typical form occurs in that state. I believe that 
most of the southern records for lineolata (especially the older ones) 
belong either to atkinsoni or the subspecies subopaca. As noted above, 
the typical lineolata occurs in the highlands of northern Georgia and 
Alabama but at lower elevations that far south it appears to be largely 
replaced by subopaca. 



14. CREMATOGASTER (ACROCOELIA) 



(new name) 



Cr. lineolata var. Emery, Zool. Jahrb. Syst., Vol. 8, p. 281 (1895) 9 . (variety 

described but included without a name under the typical form). 
Type loc: Colorado. Types: none in this country. 
Range: mountains of Colorado, New Mexico and Arizona. 



214 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

This subspecies is characterized, as Emery noted in 1895, by its 
short, thick, divergent epinotal spines, its brownish red color and its 
small size (3 mm.)- In addition the rugae on the dorsum of the thorax 
are strong and not obscured by the interrugal sculpture. 

It is interesting to note that when Emery described this insect in 
1895, he stated that if it should subsequently prove to be an alpine 
variety it should be given a name. While emeryana is scarcely an al- 
pine form, it is a mountain- dwelling subspecies. I have, therefore, fol- 
lowed Emery's suggestion and given it his name. 



15. CREMATOGASTEE (ACROCOELIA) LINEOLATA SUBOPACA Emery 

Cr. lineolata var. subopaca Emery, Zool. Jahrb. Syst., Vol. 8, p. 283 (1895) 9 . 

Type loc: Virginia. Types: none in this country. 

Range: low or moderate elevations in the South Atlantic States westward to 
Colorado and northern Texas and northward to the latitude of southern 
New England. The insect appears to be notably less abundant north of 
the latitude of Virginia. 

The subspecies subopaca combines certain features of the typical 
lineolata and punctulata. The epinotal spines of subopaca are like those 
of lineolata. The pilosity of subopaca is like that of punctulata. The 
thoracic sculpture of subopaca is intermediate between that of the 
other two subspecies. This blending of traits would certainly suggest 
that subopaca is an intergrade were it not for the fact that most of the 
range of subopaca lies in a region where neither of the other two sub- 
species occur. For this reason subopaca may be considered a dis- 
tinct subspecies and not an intergrade. It is worth noting that the 
subspecies subopaca is easier to recognize by hair pattern than by 
sculpture. This fact seems to have been generally overlooked, which 
is not surprising, since Emery based the form on sculptural characters 
only. But the thoracic sculpture of subopaca is subject to minor fluc- 
tuations over its entire range, whereas the more abundant erect hairs 
on the thorax appear to be remarkably constant except in the area 
where this subspecies intergrades with the typical lineolata. 



16. CREMATOGASTER (ACROCOELIA) LINEOLATA PUNCTULATA Emery 

Cr. punctulata Emery, Zool. Jahrb. Syst., Vol. 8, p. 287 (1895) 9 .. 

Cr. lineolata var. punctulata Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 479 (1908). 
Cr. (A.) opaca var. texana Santschi, Wien Ent. Zeitung, Vol. 46, p. 91 (1929) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA zlo 

Typeloc: Colorado. Types: none in this country. 

Range: areas of low elevation in eastern Colorado, New Mexico and western 
Texas. 

This insect certainly intergrades with subopaca in western Texas 
and, presumably, with the typical lineolata in eastern Colorado as 
well. There is, therefore, no reason why it should be given specific 
status. I believe that Santschi's variety texana is an intergrade be- 
tween punctulata and subopaca. It will probably be impossible to de- 
termine the exact nature of texana in any case. This form was de- 
scribed from a single worker and it is highly doubtful that an exam- 
ination of the type will be of much service. The insect should never 
have been described under such circumstances, but it seems reason- 
ably clear that it is not related to opaca, as Santschi supposed. The 
insect which I regard as opaca occurs only in the mountains of south- 
ern Arizona. 



17. CREMATOGASTER (ACROCOELIA) MORMONUM Emery 

Cr. lineolata subsp. coarctata var. mormonum Emery, Zool. Jahrb. Syst., Vol. 8, 
p. 284 (1895) 9 ; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 482 
(1908) 9 9 cf. 

Type loc: Salt Lake, Utah. Types: none in this country. 

Range: known only from Utah, where it occurs in the Transition Zone. 

Emery described mormonum from a few workers and this has led 
to considerable confusion as to the definitive characteristics of this 
species. In the original description of mormonum Emery pointed out 
that the antennal scapes surpass the occipital margin by an amount 
one and one half times as great as the maximum thickness of the scape. 
This character is true of the large workers of mormonum as well as 
the small ones and thus gives a good means by which mormonum can 
be separated from related species. But Emery did not stress this 
fact and the result has been that other western forms have been con- 
fused with mormonum. The smallest workers of laeviuscula, vermicu- 
lata, etc. also have long antennal scapes but this is not true of their 
large workers, in which the scape is short. Emery related mormonum 
to coarctata because of the similarity of cephalic sculpture in the two 
insects. It is possible that Emery is correct and that mormonum is an 
eastern race of coarctata. However, as I have seen nothing to indicate 
that mormonum intergrades with coarctata or with its southern sub- 
species vermiculata, it seems preferable to treat mormonum as a sep- 
arate species. It may be added that mormonum is not related to 



zlo BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

lineolata. The female of mormonum has a rectangular head, which 
is almost one third broader than long (mandibles excluded). No fe- 
male of the lineolata complex shows a comparable cephalic structure. 

18. CREMATOGASTEK (ACROCOELIA) OPACA May* 

Cr. opaca Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 989 (1870) 9 . 

Typeloc: Mexico. Types: none in this country. 

Range: mountains of southern Arizona south into Mexico. 

Wheeler believed that opaca should include punctulata and depilis 
but it seems ill-advised to treat the two latter forms as subspecies of 
opaca. It may be admitted that all three insects are heavily punctate 
and to this extent they are related. But the punctuation in opaca 
is different from that of the other two forms. This difference appears 
to depend on the fact that in opaca the bottoms of the punctures are 
dull. Its surface appears matte-like and completely opaque in con- 
sequence. In the other two forms the bottoms of the punctures are 
shining. Thus in punctulata and depilis the surface has a feebly shining 
appearance even in the areas where the punctures are densest. 



19. CREMATOGASTER (ACROCOELIA) PILOSA Emery 

Cr. lineolata subsp. pilosa Emery, Zool. Jahrb. Syst., Vol. 8, p. 285 (1895) 9 . 

Tjpeloc: District of Columbia (by present restriction). Types: none in this 
country. The specimens bearing cotype labels in the collection of the 
M.C.Z. seem to be a part of Pergande's original series and are probably 
authentic. It is not possible, however, to consider them cotypes (see 
below). 

Range: Central Atlantic States, New Jersey to North Carolina. 

In the original description of pilosa Emery attributed the name to 
Pergande who had, apparently, written him about the insect. It is 
difficult to see how Emery expected this to make Pergande the author 
of the species. Pergande never published any description of pilosa 
and the species clearly belongs to Emery, a fact which he later ac- 
knowledged. Although Emery considered pilosa to be related to lineo- 
lata, it appears to have closer affinities with atkinsoni. In the female 
of pilosa the sides of the head converge strongly in front of the eyes. 
This same condition is present in the female of atkinsoni. The dis- 
tinguishing characteristic of pilosa is, of course, its extreme hairiness. 
In this respect it differs sharply from atkinsoni, in which the hairs are 
notably sparser, particularly on the gaster. 



CREIGHTON: ANTS OF NORTH AMERICA /!/ 

Genus MONOMORIUM Mayr 
(Plate 25, figures 1-4) 

The majority of the species which belong to Monomorium occur in 
the Old World. Its representation in North America is especially 
poor. There are only two (possibly three) endemic species in the 
United States, hence our native species are outnumbered by those 
which have been imported from other areas. The species pharaonis, 
floricola and destructor are tropicopolitan 'tramps' whose origin is un- 
certain but it seems clear enough that all three have been introduced. 
The exact status of M. carbonarium subsp. ebininum is difficult to de- 
termine for this form may be a native of the Antilles and its presence 
in Florida might be due to migration rather than to importation. 
Here again, however, the roving tendency of the insect makes it im- 
possible to be sure of its status as a native form. 

All the species of Monomorium which occur in North America are 
exceptionally adaptable in the matter of nest sites. They will utilize 
all manner of preformed cavities (I once saw a nest of M. pharaonis 
which had been built inside an eye-dropper) or adapt themselves 
equally well to nesting in the soil. This adaptability is coupled with 
a wide tolerance for various sorts of environment. Our native species 
seem equally at home in the arid semi-desert regions of the west and 
the humid, heavily wooded areas of the eastern and southern states. 
The introduced species are- decidedly limited by temperature. None 
of them are able to tolerate the climatic conditions which occur over 
most of the United States, hence the majority of the field records for 
these species come from Florida or southern Texas. The northern 
records are almost invariably from greenhouses or dwellings. The be- 
havior of M. pharaonis appears to offer the only exception to this gen- 
eral rule. This active and enterprising little ant is now so widely dis- 
tributed in greenhouses throughout the country that there is ample 
opportunity for it to appear in northern stations whenever a mild 
year permits its egress. But while this insect has been taken in the 
field in stations as far north as New York, it may be doubted that 
such colonies survive unless the ants move to more sheltered quarters 
during the winter months. 



Key to the species of Monomorium 

1. The three segments which form the antennal club successively increasing 
in length; workers varying little in size, not at all dimorphic (Subgenus 

Monomorium) ! 

The first two of the three segments which form the antennal club subequal 



/! BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

in length; workers varying moderately in size and slightly dimorphic 
(Subgenus Parholcomyrmex) destructor 

2. Head and thorax densely punctate, opaque or very feebly shining; color 

clear, reddish yellow pharaonis 

Head and thorax in large part or entirely smooth, strongly shining with 
only scattered, piligerous punctures; color not as above 3 

3. The teeth which terminate the clypeal carinae distinct, with the clypeal 
edge between them bearing a marked, concave impression which is often 

carried back between the carinae as a triangular sulcus 4 

The teeth which terminate the clypeal carinae indistinct or absent, the 
clypeal edge between the carinae straight or very feebly impressed, not 
sulcate behind 6 

4. Node of the petiole, in profile, somewhat higher than its base is long with 
the anterior peduncle about as long as the base of the node; mesopleurae 

and base of the epinotum rugulose or delicately striate 5 

Node of the petiole, in profile, approximately as high as it is long with the 
anterior peduncle notably shorter than the base of the node; mesopleurae 
and the base of the epinotum for the most part smooth and shining. . . . 

minimum 

5. Clypeal teeth curved inward; length of worker 1.8-2.8 mm.; female 5.3- 
5.7 mm.; thorax of female ferrugineous, head and gaster darker, all with 

strong greenish reflections viridum 

Clypeal teeth straight; length of worker 1.8-2.0 mm.; female 4.5-5.0 mm.; 
color of female brownish black to piceous black with faint bluish reflections 
sometimes present viridum subsp. peninsulatum 

6. Node of the petiole, in profile, notably higher than its base is long, the crest 
flat or very feebly impressed in the middle when seen from behind; color 

uniform piceous black carbonarium subsp. ebininum 

Node of the petiole, in profile, lower than its base is long, the crest evenly 
convex when seen from behind; head and gaster sordid brown, thorax, 
petiolar nodes and appendages dirty yellow floricola 



Subgenus MONOMORIUM Mayr 

1. MONOMOHIUM CARBONARIUM EBININUM Forel 

(Introduced ?) 

M. carbonarium Forel (part) Mitt. Munchen. Ent. Ver., Vol. 5, p. 8 (1881) 9 . 
M. minutum var. ebininum Forel, Grandidier, Hist. Phys. Madagascar, Vol. 20, 

p. 165 (1891) 9 . 
M. carbonarium subsp. ebininum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 

24, p. 423 (1908). 

Typeloc: St. Thomas, B. W. I. and Guatemala. Types: none in this country. 
Range: scattered records from southern Florida and the Brownsville area of 

Texas. 



CREIGHTON: ANTS OF NORTH AMERICA i\) 

2. MONOMORIUM FLORICOLA (Jerdon) 
(Introduced) 

Atta floricola Jerdon, Madras Lit. Soc., Vol. 7, p. 107 (1851) 9 . 

M. floricola Forel, Jour. Bombay Nat. Hist. Soc., Vol. 14, p. 686 (1902); 

Bingham, Fauna Brit. India, Vol. 11, p. 211 (1903) 9 ; Wheeler, Bull. 

Amer. Mus. Nat. Hist., Vol. 21, p. 87, fig. d, e (1905) 9 ; Emery, Deutsche 

Ent. Zeitschr., p. 664 (1908) 9 9 . 

M . poedlum Roger, Berl. Ent. Zeitschr., Vol. 7, p. 199 (1863) 9 9 . 
Type loc: India. Types: none in this country. 
Range: southern Florida. 

3. MONOMORIUM MINIMUM (Buckley) 

M. minutum Mayr, Sitz. Akad. Wiss. Wien, Vol. 53, p. 506 (1866) 9 (nee 

M. minutum Mayr, 1855). 

Myrmica minimum Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 338 (1867) 9 9 . 
M. minutum var. minimum Emery, Zool. Jahrb. Syst., Vol. 8, p. 274 

(1895) 9 9 tf 1 . 
M. minutum subsp. minimum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 423 (1908). 
M. minimum Wheeler, Jour. N. Y. Ent. Soc., Vol. 22, p. 42. (1914); M. R. 

Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 564, pi. 8, fig. 31 (1947) 9 . 
M. minutum subsp. ergatogyna Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, 

p. 269 (1904) 9 9 . 

M . minutum subsp. emersoni Gregg, Psyche, Vol. 52, p. 66 (1945) 9 9 . 
Type loc: Texas. Types: none known to exist. 

Range: southeastern Canada and the northeastern United States southwest- 
ward to the Pacific coast. The insect appears to be extremely rare or 

absent over much of the Pacific northwest. 

The writer can see no justification for the recognition of Wheeler's 
subspecies ergatogyna or Gregg's subspecies emersoni, both of which 
have been treated here as synonyms of minimum. 

The discussion covering the above synonymy can be somewhat 
simplified if it is realized that the taxonomy of minimum has recently 
undergone a significant change. In 1943 Brown described a new species 
of Monomorium which he called viridum and two years later Gregg 
added another, M . peninsulatum. It is my belief that peninsulatum 
is a southern race of viridum, but this is beside the point. Both these 
forms are dark-colored insects and both resemble minimum closely. 
Hence, it is now no longer possible to hold that any black form of 
Monomorium occurring in the United States (except the introduced 
ebininum) must be referred to minimum. As I shall attempt to show 
in the following paragraphs, this previously accepted dogma has been 



/zu BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

directly responsible for the recognition of ergatogyna and indirectly 
for that of emersoni. 

It happens that the insect which Gregg called peninsulatwn occurs 
widely in Texas and this ant may have been the form to which Buck- 
ley gave the name minimum. This seems impossible of exact deter- 
mination but it is quite possible to show that it is the insect which 
Wheeler called minimum in 1904. At that time Wheeler's concept of 
minimum was based largely on specimens coming from Texas. Since 
he assumed that these Texas specimens were identical with Buckley's 
species, Wheeler was able to set up several infraspecific variants which 
differed slightly from what he regarded as the 'typical' minimum. 
Of these we need concern ourselves only with the subspecies ergatogyna. 
The circumstances under which this form was recognized are certainly 
unusual from a taxonomic standpoint. Wheeler made practically no 
effort to distinguish the worker of ergatogyna from that of minimum, 
contenting himself with the statement that they are 'merely some- 
what smaller'. But Wheeler laid considerable stress on the differences 
shown by the female of ergatogyna and particularly on the fact that he 
considered this insect to be an ergatogyne. As will be shown later, 
all that this meant was that the female had never had wings. But 
since the type material of ergatogyna came from Catalina Island, 
Wheeler ingeniously developed the theory that this aptery was an 
adaptation to life on an oceanic island. It may be stated at once that 
this latter view has since been shown to be untenable. Apterous fe- 
males, agreeing in all respects with those of ergatogyna have been se- 
cured at many mainland stations in western states. In addition, I 
have in my possession a series of females which Professor Cockerell 
secured on San Miguel Island. Most of these are in all respects com- 
parable to Wheeler's specimens and show no signs that they have ever 
had wings. Indeed, one of them is a callow, a fact which allows no 
chance that the wings might have been present. But two of the series 
may, in my opinion, have had wings originally. The epimera are not 
fused with the scutum, as is the case with the apterous forms, and 
there are small projections present which look very much like the 
stumps of hind wings. It would appear, therefore, that ergatogyna 
does not always have apterous females and that there is no connection 
between the aptery of its female and life on an oceanic island. Finally, 
it is quite impossible to regard ergatogyna as an insular subspecies. 

But these are by no means the only misconceptions which Wheeler 
held in regard to ergatogyna. It is my opinion that the female of this 
insect cannot properly be considered as an ergatogyne. In 1904, and 
for some years thereafter, Wheeler's concept of an ergatogyne was 
exceedingly liberal. According to the definition which Wheeler gave 
in 1910, an ergatogyne is 'a workerlike form with ocelli, large eyes 



CEEIGHTON: ANTS OF NORTH AMERICA 221 

and a thorax more or less like that of the female but without wings'. 
There are some remarkable points in this definition. A female ant 
ordinarily has ocelli. Its eyes are customarily larger than those of 
its workers. If the thorax of an ergatogyne is like that of the female, 
then it follows that the only workerlike character cited by Wheeler 
is the lack of wings. Why then, should such an insect be called an 
ergatogyne? Needless to say, other myrmecologists have held a more 
restricted view as to the nature of the ergatogyne. As Emery em- 
ployed the term it denotes a fertile female with a worker-like thorax. 
In fully developed ergatogynes, for example those which occur in the 
genus Leptogenys, the thorax is typically that of the worker. Indeed, 
the principal external difference between the ordinary worker and 
such ergatogynes is the more voluminous gaster of the latter. Hence 
it may be contended that the specimens which Wheeler regarded as 
ergatogynic females of ergatogyna do not deserve to be so considered. 
Their thoraces are typically female even to the presence of the smaller 
alar scutes. As noted above, the mesothoracic epimera are fused with 
the scutum but this seems to be the only feature which will distinguish 
these females from the normal type once the latter has been dealated. 
It seems plain enough that the females which Wheeler described 
could never have had wings, but aptery alone is not enough to make 
a female an ergatogyne. 

I have stressed this point because it is my opinion that Wheeler 
secured a fallacious distinction in the case of ergatogyna by the use of 
the term ergatogyne. Most myrmecologists would, under the cir- 
cumstances, expect a notable structural difference in the thorax of 
the female. Unless one has been able to examine the types of erga- 
togyna it is not apparent that, except for the minor differences men- 
tioned above, the insects are exactly like the females of that form of 
minimum which occurs in the northeastern United States. It seems 
plain that Wheeler never clearly realized this fact. In 1914 he pre- 
sented a brief description of the female of minimum in which the in- 
sect is characterized as having a length of 4.5 mm. with the head sub- 
opaque, longitudinally striate in front and coarsely punctate over the 
whole upper surface with the petiole distinctly pedunculate. This is 
obviously the insect which Gregg later described as pcninsulatum. It 
is, of course, quite different in structure from the female of erga- 
togyna, but Wheeler was willing to assign to minimum specimens 
coming from the northern and northeastern United States whose 
structure agrees much more closely with that of ergatogyna than with 
that of the insect which Wheeler called minimum. The confusion on 
this point seems to have been the main reason for Gregg's description 
of the subspecies emersoni. The writer cannot see how this insect can 
be separated from ergatogyna for, as has been shown above, there is 



222 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

reason to believe that the female of that form sometimes has wings 
and the presence of wings is the principal difference which Gregg used 
to distinguish emersoni from ergatogyna. Gregg's attempt to compare 
emersoni with the 'typical' minimum means very little for, if he was 
using Wheeler's criteria of the 'typical' minimum, he was comparing 
emersoni with his own peninsulatum. I do not believe that this was 
the case, but it is clear that as things stand at present the 'typical' 
minimum is largely what the observer chooses to make it. 

There is little need to point out that this tangle calls for clarifica- 
tion. For the time being it seems hopeless to determine whether 
ergatogyna or peninsulatum is the same as Buckley's minimum, al- 
though one or the other must be identical with Buckley's species. 
Since both occur in Texas Buckley might have described either. But 
his description is worthless, even to indicate the genus, and if Mayr 
had not had specimens from Buckley it is probable that minimum 
would never have been recognized as a Monomorium. Under the cir- 
cumstances there are two solutions possible. We can follow Wheeler 
in regarding as the typical minimum the insect which Gregg later 
described as peninsulatum. If this is done peninsulatum sinks as a 
synonym and Brown's viridum becomes a northern subspecies of 
minimum. But it will then be necessary to give specific status to 
ergatogyna and to include in this species much of the material which 
has previously been assigned to minimum. I regard this plan as un- 
satisfactory because of the confusion it is certain to produce. Speci- 
mens coming from the northern and eastern United States have been 
treated as minimum for so long that it cannot fail to cause trouble if 
the name is changed to ergatogyna. I have, therefore, followed the al- 
ternate plan of regarding Wheeler's ergatogyna as identical with 
Buckley's minimum. This enables peninsulatum to stand as a southern 
subspecies of viridum and, what is more important, preserves the 
name minimum for our common northeastern species of Monomorium. 
It should be borne in mind, however, that if the specimens which 
Buckley sent to Mayr are still in existence, an examination of these 
specimens may subsequently force an adoption of the first plan out- 
lined above. 

4. MONOMORIUM PHARAONIS (Linne) 
(Introduced) 

Formica pharaonis Linne, Syst. Natur. Ed. 10, Vol. 1, p. 580 (1758) 9 . 

M. pharaonis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 752 (1862); Mayr, 
Reise Novara, Formicid, p. 90 (1865) rf 1 ; Mayr, Tijdschr. v. Ent., Vol. 10, 
p. 95 (1867) 9 9 c? ; Saunders, Trans. Ent. Soc. Lond., p. 222 (1880) 
9 9 d"; E. Andre, Spec. Hym. Europe, Vol. 2, p. 333 (1882) 9 9 d"; 



CREIGHTON: ANTS OF NORTH AMERICA ZZ6 

Bellevoye, Soc. Etudes Sci. Nat. Reims, Vol. 1, p. 21 (1891) 9 9 d"; 
Forel, in Grandidier, Hist. Phys. Madagascar, Vol. 20, 2, p. 1,63 (1891) 
9 Q'C?; Forel, Jour. Bombay Nat. Hist. Soc., Vol. 14, p. 686 (1902) 9 ; 
Bingham, Fauna Brit. India, Hym., Vol. 2, p. 201 (1903) 9 9 ; Ruzsky, 
Formic. Imp. Rossici, Vol. 1, p. 633, figs. 160-162 (1905) 9 9 d" ; Emery, 
Deutsche Ent. Zeitschr., p. 664 (1908) 9 9 cf ; Donisthorpe, British 
Ants, p. 96, pi. 6 (1915); Forel, Fauna. Ins. Helvet. Formicid., p. 39 
(1915); Emery, Bull. Soc. Ent. Ital., Vol. 47, p. 161 (1916) 9 9 d 1 ; Ar- 
nold, Ann. S. African Mus., Vol. 14, p. 228 (1916) 9 9 d". 

Type loc: India? Types: none in this country. 

Range: widespread in greenhouses and dwellings throughout the country. 
The insect has been able to adapt itself to field conditions in southern 
Florida. 

In addition to the bibliographic citations presented above, M. 
pharaonis has been repeatedly described under other generic and 
specific names. Since the value of most of these descriptions is slight 
the references to them have not been included here. For a full biblio- 
graphy of pharaonis see the Genera Insectorum, Fasc. 174, p. 173 (1921). 



5. MONOMORIUM VIRIDUM Brown 

M. viridum Brown, Ent. News, Vol. 54, No. 10, p. 243 (1943) 9 9 . 
Type loc: Lakehurst, New Jersey. Types: Coll. W. L. Brown. 
Range: known only from type material. 

Before Mr. Brown described viridum, he very kindly gave me speci- 
mens of this insect. I believe that these were a part of what later be- 
came the type series. The relationship of viridum to minimum has 
been discussed on a preceding page and need not be repeated here. 
Since viridum is at present known only from the type locality, nothing 
positive can be said at this time about its range. It seems probable, 
however, that the types were taken in the northern portion of the 
range. It will, I believe, not be easy to plot the range of viridum for 
the worker of this form is exceedingly like that of its southern sub- 
species peninsulatum and for certain separation of the two forms it 
will probably be necessary to secure the females. Unfortunately, the 
distinctive green coloration which is present in the female of viridum 
is not shown to any extent by the worker. 



6. MONOMORIUM VIRIDUM PENINSULATUM Gregg 

M. peninsulatum Gregg, Psyche, Vol. 52, No. 1, p. 62 (1945) 9 9 . 
Type loc: South Miami, Florida. Types: Coll. R. E. Gregg, A.M.N.H. 
Range: Florida and the Gulf Coast States and west to Arizona. In the west 
the northern limit of the range appears to lie in southern Colorado. 



zz4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The relationship of peninsulatum to minimum and the reasons for 
treating it as a subspecies of viridum have been discussed on a previous 
page. 

Subgenus PARHOLCOMYRMEX Emery 

7. MONOMOEIUM (PARHOLCOMYRMEX) DESTRUCTOR (Jerdon) 
(Introduced) 

Atta destructor Jerdon, Madras Jour. Lit. Soc. ,Vol. 17, p. 105 (1851) V . 

M. destructor Forel, Jour. Bombay Nat. Hist. Soc., Vol. 14, p. 686 (1902) 9 ; 

Bingham, Fauna Brit. India, Hym., Vol. 2, p. 201 (1903) 9 9 tf; Emery, 

Deutsche Ent. Zeitschr., p. 665 (1908) 9 9 ; M. R. Smith, Amer. Mid. 

Naturalist, Vol. 37, No. 3, p. 566, pi. 8, fig. 33 (1947) 9 . 
Myrmica vastator F. Smith, Jour. Proe. Linn. Soc. Lond. Zool., Vol. 2, p. 71 

(1857); F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 123 (1858) 9 ; Mayr, 

Verh. Zool-bot. Ges. Wien, Vol. 36, p. 359 (1886). 
Myrmica basalis F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 125 (1858) 9 ; 

Mayr, Reise Novara, Formicid., p. 92 (1865) 9 ; Emery, Ann. Mus. 

Stor. Nat. Geneva, Vol. 16, p. 532 (1881) 9 . 
Type loc : India. Types : none in this country. 
Range : Florida and Tennessee. 

As with most of the other introduced species of Monomorium it is 
probable that destructor makes permanently established nests out of 
doors only in Florida. 



Genus XENOMYRMEX Forel 
(Plate 26, figures 1-4) 

Our only representative of this small but interesting Neotropical 
genus is X. stolli floridanus Emery which occurs in the southern part 
of Florida. The rarity of these insects and their discontinuous dis- 
tribution has considerably limited our knowledge of their habits. 
There seems to be little doubt, however, that they form their small 
colonies in the cavities of twigs. The structure of the female shows a 
marked adaptation to such a type of habitat. The slender thorax and 
long, narrow abdomen of the Xenomyrmex female are strikingly sim- 
ilar to those of the females of certain twig-dwelling species of Solen- 
opsis (picta etc.). To a lesser extent, these modifications are shown by 
the worker and male. This latter caste is remarkably small in contrast 
to the size of the female. 



CKEIGHTON: ANTS OF NORTH AMERICA zzo 

The worker and female of Xenomyrmex may be distinguished from 
the corresponding castes of Solenopsis, which they superficially re- 
semble, by the eleven jointed antennae. Emery, in the Genera In- 
sectorum, notes that Xenomyrmex possesses a three-jointed antennal 
club. While it is true that the antepenultimate joint of the funiculus 
is somewhat larger than the preceding joints it is much less bulky than 
the two terminal joints. This is particularly true of the worker which, 
in my estimation, could as well be regarded as possessing a two- 
jointed antennal club. The petiole of the female is notably rectangu- 
lar in shape with scarcely any indication of a node above. Mayrian 
furrows are absent in the female. 

The male of Xenomyrmex appears to be an extraordinarily delicate 
insect. There have been three specimens of this caste described and 
all of them have been more or less damaged. Emery's original des- 
scription of the male cfi floridanus was based upon a damaged specimen 
and the two males belonging to this genus which the writer has ex- 
amined (one of the subspecies skwarrae, the other of the subspecies 
casta) have both had the upper surface of the head caved in. It seems 
entirely possible that these damages are due to the thin integument 
of the male which collapses on drying. I mention this point because 
I have redrawn the single male of skwarrae on which Dr. Wheeler 
based his illustration published in 1932. My drawing is so unlike that 
of Dr. Wheeler that I would hesitate to believe that he utilized the 
same insect were it not the only one in the type series. A possible 
explanation lies in the supposition that Dr. Wheeler assumed that the 
cephalic damages of the male of skwarrae extended to the thorax as 
well. This is not the case. The shape of the thorax in the male of 
skwarrae is certainly peculiar but this is not due to damage to the 
thoracic sclerites. Unless I am very much mistaken, Dr. Wheeler 
attempted to reconstruct an "ideal" thorax for the male of skwarrae. 
In the illustration presented here no attempt has been made to com- 
pensate for such damage to the head as has been caused by drying. 
This may be misleading but at least the picture is an accurate replica 
of the type of skwarrae. I have utilized this related Mexican sub- 
species in the case of the male caste because there are no males of 
floridanus available. One further point relates to the presence of May- 
rian furrows in the male of skwarrae. Emery described the male of 
floridanus as doubtfully possessing these structures. This seems cu- 
rious in view of their very prominent development in the male of 
skwarrae. We are badly in need of more data concerning the males of 
Xenomyrmex. 

Finally, I have synonymized Wheeler's subspecies rufescens with 
floridanus. The subspecies rufescens was based upon a single dealated 



Zzo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

female which Wheeler took at Long Pine Key, Florida. It appears 
to be a very minor color variety of the typical floridanus. The head, 
thorax and petiolar nodes of the subspecies rufescens are reddish 
yellow while those of floridanus are blackish brown. Wheeler stated 
that the head and thorax of rufescens are wider than those of flori- 
danus, but I cannot agree that this is the case. Careful micrometer 
measurements of the thorax of the type of rufescens give proportions 
that are identical with those of the females which Wheeler used as 
the basis for his description of the typical floridanus. I can see no 
difference in the two insects except color and this difference is cer- 
tainly not suitable for subspecific distinction, especially when both 
insects come from southern Florida. 



1. XENOMYRMEX STOLLI FLORIDANUS Emery 

X. stolli subsp. floridanus Emery, Zool. Jahrb. Syst., Vol. 8, p. 275 (1895) V c? ; 

Wheeler, Revist. Ent,, Vol. 1, fasc. 2, p. 135, fig. 2 a-d (1931) 9 9 d* ; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 566, pi. 8, 

fig. 33 (1947) 9 . 

X. stolli subsp. rufescens Wheeler, Revist. Ent., Vol. 1, fasc. 2, p. 137 (1931) 9 . 
Type loc: Lake Worth, Florida. Types: U.S.N.M., M.C.Z. 
Range: known only from southern Florida. 



Genus SoLENOPSIS Westwood 
(Plate 27, figures 1-6) 

The student of North American ants may count himself fortunate 
that so few species of this difficult genus occur in our latitudes. He is 
thus saved from the task of trying to distinguish the many tropical 
species whose worker caste shows an astonishing and baffling con- 
vergence. This problem is largely confined to the small monomorphic 
species belonging to the subgenus Diplorhoptrum. In general the 
larger species, particularly those which are polymorphic, may be 
distinguished readily enough. But this is mainly because of the 
structure of the large workers. Even in the polymorphic species there 
is a notable convergence of form in the case of the minor workers. 
This has placed a somewhat greater stress than is usually the case on 
the structure of the sexual forms. Both male and female castes appear 
to offer much better characters for specific determination than do the 
workers in many cases. The females of a fair number of species are 
known but we are sadly lacking in adequate knowledge of the male 
caste. When this is forthcoming extensive changes in the taxonomy 
of this group may be necessary. 



CREIGHTON: ANTS OF NORTH AMERICA 



In view of the structural uniformity which exists within the genus, 
these insects show a range of habits which is rather surprising. At 
one extreme we have the large and aggressive colonies of such species 
as geminata and saevissima. These insects prefer to make their nests 
in soil, although they will sometimes utilize rotten logs, and the nest 
is usually surmounted by a ragged mound of excavated soil. The 
workers forage actively and are pugnacious in the extreme. They 
have a particularly painful sting which accounts for their popular 
name of "fire ant". Wherever they occur they are a dominant note 
in the environmental picture and they are among the few species of 
ants which can justifiably be regarded as serious pests. Because of 
their omnivorous habits they are always turning up in unexpected 
situations. They have been known to damage the buds and tender 
twigs of young fruit trees and kill quail which are too young to leave 
the nest. In certain areas they are a chronic nuisance because their 
unsightly nests disfigure lawns. 

At the other extreme one finds a number of small, monomorphic 
species, several of which are known to be thief ants. Their colonies are 
usually founded in close proximity to the nest passages of some larger 
species with which the tiny passages from the nest of the thief ant 
communicate. A steady pilfering of brood or other food from the nest 
of the larger species is carried on in such obscurity that the larger 
species rarely seems aware of its loss. These thief ants only occa- 
sionally forage above ground and are almost impossible to see when 
they do so because of their minute size. It has been my observation 
that these tiny insects are just as bad tempered and pugnacious as 
their larger congeners but their stings are so small that they have no 
effect on human skin. 

Another common habit pattern among the small species of Solen- 
opsis results from the preference for living in preformed cavities in 
plant tissue. They will sometimes inhabit hollow galls but more often 
they prefer to nest in twigs having a hollow pith cavity. The female 
of at least one species (picta) has an unusually narrow thorax and, 
while it may be only a coincidence that this species lives in hollow 
twigs, at least the thoracic structure of the female would enable her 
to move around more freely under such circumstances. 

It is interesting to note that xerophilous or semi-xerophilous spe- 
cies have been produced in all three subgenera which occur in North 
America. S. (Solenopsis) aurea and its subspecies amblychila are 
known only from regions of great aridity in the southwestern United 
States and northern Mexico. The insect which Wheeler described 
as maniosa also shows a strong preference for desert life. But since 
this form is virtually identical with the eastern xyloni, which is cer- 



ZZ5 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

tainly not xerophilous, it may be that the nesting habits of maniosa 
merely indicate a tolerance for a wide range of stations rather than a 
marked xerophily. So little is known about S. (Eiiophthalma) huachu- 
cana that any statement regarding its habits must be largely specula- 
tive. However, the fact that the type colony was taken at low levels 
in the Huachuca Mountains would seem to indicate at least a semi- 
xerophilous existence. Finally, we have three species which belong to 
the subgenus Diplorhoptrum, krockowi, pilosula and salina. None of 
these species is well known but our meager data seem to indicate a 
tendency towards xerophily in all three. It is worth noting that some 
~t +u oc . ^00,.+ ^^,^11,-r, species are known to be crepuscular in habit. 



Key to the species of Solenopsis 

1. Second and usually the third funicular joint of the worker at least one and 

one-half times as long as broad (Subgenus Solenopsis) 2 

Second and third funicular joints of the worker at most very slightly 
longer than broad, usually broader than long 7 

2. Mandibles of the major and the larger medias abruptly curved, the teeth 

aborted or absent 3 

Mandibles in all sizes of workers gradually curved with three or four well- 
developed teeth 4 

3. Thorax bearing a mesoternal spine or projection. . .geminata subsp. rufa 
Mesosternum of the thorax without a spine or projection geminata 

4. The tip of the antennal scape of the minor worker surpassing the occipital 

border saevissima subsp. richteri 

The tip of the antennal scape of the minor worker not surpassing the occi- 
pital border 5 

5. Eyes of the major consisting of 70-80 facets (about 50 in the minor) and 
separated from the insertion of the mandibles by a distance one and one 

half times as great as the maximum diameter of the eye xyloni 

Eyes of the major consisting of not more than 50 facets (about 20 in the 
minor) and separated from the insertion of the mandibles by a distance 
twice as great as the maximum diameter of the eye f 

6. Clypeal teeth present in the major aurea 

Clypeal teeth absent in the major aurea subsp. amblychila 

7. Eyes of the worker composed of twenty or more facets, or if less are pres- 
ent, the postpetiole is greatly dilated (Subgenus Euophthalma) 8 

Eyes of the worker with not more than fifteen facets present at most, and 
usually less than ten present (Subgenus Diplorhoptrum) 9 

8. Postpetiole greatly dilated, more than half as wide as the gaster; epinotum 

finely and densely sculptured globularia subsp. littoralis 

Postpetiole not dilated, scarcely more than one-third as wide as the 
gaster; epinotum smooth and without sculpture huachucana 

9. Head covered with numerous small but distinct punctures which are 



CREIGHTON: ANTS or NORTH AMERICA 



clearly greater in diameter than the hairs which rise from them 10 

Cephalic punctures sparser and smaller, often visible only under high 
magnification and not much larger in diameter than the hairs which rise 
from them 14 

10. Postpetiole seen from above circular or nearly so, color pale yellow to 

milky white 11 

Postpetiole seen from above not circular in outline, the front or rear face 
or both faces somewhat flattened 12 

11. Head (mandibles excluded) distinctly longer than broad; the antennal 
scapes not extending more than two-thirds the distance to the occipital 

corners longiceps 

Head (mandibles excluded) usually square, at most very slightly longer 
than broad; the antennal scapes extending a little more than three-quar- 
ters of the distance to the occipital corners pergandei 

12. Node of the petiole seen from above a little wider than the postpetiole, 

and with a slightly concave posterior face pilosula 

Node of the petiole seen from above not wider than the postpetiole, its 
posterior face not concave 13 

13. Anterior peduncle of the petiole with a prominent, sharp, ventral tooth . . 

salina 

Anterior peduncle of the petiole with the ventral tooth blunt and com- 
pressed krockowi 

14. Mesoepinotal suture of the thorax broadly impressed so that in profile 
the dorsum of the promesonotum is distinctly set off from that of the 
epinotum, the latter very broadly rounded and without a clear distinc- 
tion between the basal and declivious faces; color piceous brown to black; 

thorax of the female slender picta 

Mesoepinotal suture of the thorax not impressed so that in profile the 
dorsum of the promesonotum is confluent with that of the epinotum ex- 
cept for the narrow suture itself, epinotum more or less rounded at the 
junction of the basal and declivious faces but the faces clearly distinct; 
color pale yellow to castaneous brown; thorax of the female not slender. 15 

15. Female with very large eyes which cover more than half the sides of the 

head carolinensis 

Female with smaller eyes which do not cover half the side of the head . . 16 

16. Funicular joints 3, 4 and 5 of the worker notably broader than long, color 
pale yellow, the gaster of the female a pinkish orange in living specimens 

17 

Funicular joints 3, 4 and 5 only a little broader than long, color golden 
yellow or darker, the gaster of the female not pinkish orange in living 
specimens 18 

17. Pilosity very sparse, gastric segments of the worker not infuscated 

texana subsp. catalinae 

Pilosity of medium abundance, gastric segments of the worker slightly 
infuscated texana 

18. Length 2-2.5 mm.; head subquadrate, only slightly longer than broad; 
color deep castaneous brown truncontm 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Length never in excess of 2 mm., usually less; head distinctly longer than 

wide; color golden yellow to sordid brownish yellow 19 

19. Length 1.5-1.7 mm.; color clear golden yellow (eastern and central 

states) molesta 

Length 1.8-2 mm.; color sordid brownish yellow (western states) 

molesta subsp. validiuscula 

Subgenus SoLENOPSIS Westwood 
1. SOLENOPSIS AUKEA Wheeler 

S. geminata var. aurea Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 336 
(1906) 9 9 ; Wheeler, Ibid., Vol. 24, p. 425 (1908) 9 cf . 

S. aurea Forel, Deutsche Ent. Zeitschr., p. 269 (1909). 

S. xyloni subsp. aurea Creighton, Proc. Amer. Acad. Arts Sci., Vol. 66, No. 2, 
p. 103, pi. 2, fig. 2 (1930) 9 9 cf . 

Typeloc: Mt. Bonnel, Austin, Texas. Types: M.C.Z. 

Range: desert areas in western Texas, New Mexico and Arizona. 

2. SOLENOPSIS AUREA AMBLYCHILA Wheeler 

S. aurea subsp. amblychila Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 394 (1915) 9 . 
S. xyloni subsp. amblychila Creighton, Proc. Amer. Aead. Arts Sci., Vol. 66, 

No. 2, p. 104, pi. 3, fig. 3 (1930) 9 9 <?. 

Type loc: Huachuca Mts., Ariz. Types: M.C.Z., Coll. W. S. Creighton. 
Range: mountains of southern Arizona into northern Mexico. 

In 1930 I treated aurea and amblychila as subspecies of xyloni. 
Subsequent field work has, however, convinced me that Forel was 
correct in regarding aurea as a separate species. I have now collected 
in several areas where both xyloni and aurea occur and have never 
found any intergrades in such areas. Intergrades between aurea and 
amblychila are by no means uncommon. In addition to the lack of 
intergrades between aurea and xyloni, the two show a rather constant 
difference in nest construction. The nests of aurea and its subspecies 
amblychila are usually built in fully exposed positions in dry, coarse, 
gravelly soil and without any mound of heaped-up material above the 
nest. The nests of xyloni are usually built in sandy soil rather than 
gravel with an irregular mass of excavated soil surmounting the nest. 
The nests are often situated along stream bottoms and in the east, at 
least, they are frequently built in moderately shady positions where 
the sand is decidedly damp. In the vicinity of Ft. Davis, Texas, where 
the two species occur together, the nests of aurea were on the tops of 
exposed shoulders above stream bottoms while those of xyloni oc- 
curred in the sandy draw of the stream bottom. 



CREIGHTON: ANTS OF NORTH AMERICA ^01 

3. SOLENOPSIS GEMINATA (Fabricius) 

Atta geminata Fabricius, Syst. Piez., p. 423 (1804) 9 . 

Formica geminata Roger, Berl. Ent. Zeitschr., Vol. 6, p. 289 (1862) 9 9 cf. 

Solenopsis geminata Mayr, Tijdschr. v. Ent., Vol. 10, p. 109 (1867) 9 9 <? ; 
Forel, Mitt. Miinchen Ent. Ver., Vol. 5, pi. 10 (1881) 9 cf; Creighton, 
Proc. Amer. Acad. Arts. Sci., Vol. 66, No. 2, p. 60, pi. 1, figs. 1, 4, 5, 6, 
10, 11, 12 (1930) 9 9 c?. 

Solenopsis mandibularis Westwood, Ann. Mag. Nat. Hist., Vol. 6, p. 87, 
pi. 2, fig. 5 (1841) 9 . 

Myrmica virulens F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 132 (1858). 

Atta clypeata F. Smith, Ibid., Vol. 6, p. 169 (1858) 9 cT. 

Diplorhoptrum drewseni Mayr, Europ. Formicid, p. 71 (1861) 9 . 

Myrmica glaber F. Smith, Trans. Ent, Soc. Lond. (3), Vol. 1, p. 34 (1862) 9 . 

Myrmica polita F. Smith, Ibid., Vol. 1, p. 34 (1862) 9 . 

Typeloc: "Meridional America". Types: none in this country. 

Range: the main range of this insect lies in Central America and the Antilles. 
In the United States it occurs from Texas to South Carolina. The majority 
of these records come from areas on or near the coast. As one goes inland 
the incidence usually decreases except in Florida, where the insect seems 
to be uniformly distributed over the entire state. 



4. SOLENOPSIS GEMINATA RUFA (Jerdon) 
(Introduced?) 

Atta rufa Jerdon, Madras Jour. Lit. Sci., Vol. 17, p. 106 (1851) 9 . 
Solenopsis geminata Emery, Bull. Soc. Ent. Ital., Vol. 23, p. 166 (1892). 
Solenopsis geminata subsp. re/a Forel, Jour. Bombay Nat. Hist. Soc., Vol. 14, 

p. 686 (1902) 9 ; Creighton, Proc. Amer. Acad. Arts Sci., Vol. 66, No. 2, 

p. 66, pi. 1, figs. 7, 8 (1930) 9 9 d* . 
Solenopsis geminata var. re/a Forel, Deutsche Ent. Zeitschr., p. 268 (1909); 

Bingham, Fauna Brit. India, Hym., Vol. 2, p. 158, fig. 64 (1903) 9 9 <?. 
Solenopsis cephalotes F. Smith, Jour. Proc. Linn. Soc. Lond. Zool., Vol. 3, 

p. 149 (1858) 9 . 

Crematogaster laboriosus F. Smith, Ibid., Vol. 4, suppl. p. 109 (1860) 9 . 
Solenopsis geminata var. diabola Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 

24, p. 424 (1908) 9 . 

Type loc: southern India. Types: none in this country. 
Range: largely coincidental with that of the typical form in the United States. 

In India and many parts of the East Indies re/ft is the only form present. 

It is difficult to evaluate the true status of rufa, which was at first 
regarded as native to southern Asia. As I attempted to show in 1930, 
this is a debatable point, since the American records give little evi- 
dence that rufa has been introduced here. The virtually coincidental 



232 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

ranges of rufa and the typical geminata make it impossible to treat 
rufa as a geographical race and the fact that it intergrades with the 
typical geminata makes it equally difficult to treat rufa as a separate 
species. I am inclined to believe that the value of the mesosternal 
spine as a separatory character for rufa has been given more prom- 
inence than it deserves, because of the fact that rufa was first de- 
scribed from Asiatic specimens. These specimens are more constant 
in this character than those coming from the United States. In this 
country rufa behaves as a color variety and shows no geographical 
distinctions. I have retained it as a subspecies because this behavior 
may be a result of introduction. 

5. SOLENOPSIS SAEVISSIMA EICHTERI Forel 

(Introduced) 

S. -pylades var. richieri Forel, Deutsche Ent. Zeitschr., p. 267 (1909) V 9 . 
S. saievissima var. richteri Santschi, Physis Buenos Aires, Vol. 2, p. 381 (1916); 

Creighton, Proc. Amer. Acad. Arts Sci., Boston, Vol. 66, No. 2, p. 87 

(1930) 9 9 <7. 

Typeloc: Buenos Aires, Argentina. Types: none in this country. 
Range: southern Alabama and Mississippi. 

This insect was first reported from Mobile, Alabama, in 1930. 
It has since spread considerably and has become a serious pest in 
some areas. It constructs large mound nests which frequently cause 
damage to lawns. It is also said to damage the buds of shrubs and 
young fruit trees. 



6. SOLENOPSIS XYLONI McCook 

S. xyloni McCook, in Comstock's Rep. Cotton Worm, p. 188, fig. 47 (1879) 

99. 
S. geminata subsp. xyloni Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 395 



S. xyloni Creighton, Proc. Amer. Acad. Arts Sci., Boston, Vol. 66, No. 2, p. 99, 

pi. 3, figs. 1, 4-8 (1930) 9 9 <J; M. R. Smith, Amer. Mid. Naturalist, 

Vol. 37, No. 3, p. 568, pi. 9, fig. 34 (1947) 9 . 
S. geminata subsp. maniosa Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 396 (1915) 9 9 d".' 
S. xyloni var. maniosa Creighton, Proc. Amer. Acad. Arts Sci., Vol. 66, No. 2, 

p. 102 (1930) 9 9 rf 1 . 

Type loc: none given, presumably Texas. Types: none known to exist. 
Range: South Carolina westward to California. There are no records of 

xyloni from Florida at present, although it must certainly occur in the 

region near Pensacola. 



CREIGHTON: ANTS OF NORTH AMERICA 266 

In my 1930 monograph of Solenopsis I gave reasons for believing 
that maniosa was closely related to xyloni. At that time the records 
seemed to indicate that it might be possible to treat the two as eastern 
and western races although, as I pointed out, the only difference lay 
in the lighter color of the minor worker of maniosa. Additional field 
work has convinced me that this difference is not reliable. While the 
minor worker of the typical xyloni is uniformly dark, that of maniosa 
is not always light. Since there seems to be no way of correlating these 
color variations with distribution, I have treated maniosa as a synonym 
of xyloni. 

Subgenus ElTOPHTHALMA Creighton 

7. SOLENOPSIS (EUOPHTHALMA) GLOBULARIA LITTORALIS Creighton 

S. (E.) globularia subsp. littoralis Creighton, Proc. Amer. Aoad. Arts Sci., 
Boston, Vol. 66, No. 2, p. 113, pi. 6, fig. 3 (1930) 9 9 ; M. R. Smith, 
Amer. Mid. Naturalist, Vol. 37, No. 3, p. 568, pi. 9, fig. 35 (1947) 9 . 

Type loo: Baldwin County, Alabama. Types: M.C.Z., Coll. M. R. Smith, 
Coll. W. S. Creighton. 

Range: Southern Atlantic Coast and the Gulf Coast from Florida to Mexico. 
In Alabama and Mississippi I have never taken this insect anywhere 
except on open beaches. The nests are usually constructed in or under 
rotten logs. 

8. SOLENOPSIS (ETJOPHTHALMA) HUACHUCANA Wheeler 

S. huachucana Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 393 (1915) 

9 9. 
S. (E.) huachucana Creighton, Proc. Amer. Acad. Arts. Sci., Boston, Vol. 66, 

No. 2, p. 119, pi. 7, figs. 5, 6, 7 (1930) 9 9 . 
Type loc: Miller Canyon, Huachuca Mountains, Arizona. Types: M.C.Z., 

Coll. W. S. Creighton. 
Range: known from type material only. 



Subgenus DlPLORHOPTRUM Mayr 

Before presenting the list of species which belong to the subgenus 
Diplorhoptrum, I wish to discuss certain revisionary changes which 
have been necessary in that group. On a previous page I have pointed 
out the difficulties which result from the convergence in the worker 
caste of the small species. To this may be added the further obstacle 
of their minute size. Since few of them exceed two millimeters in 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



length, size differences must be expressed in very small fractions of a 
millimeter. As a result, distinctions based on such differences are less 
reliable than is usually the case. Yet the major trouble is due to nei- 
ther of the above causes but rather to the avoidance of full descrip- 
tion of these tiny ants by the myrmecologist. Far too many sub- 
specific variants have been set up on the basis of a brief comparison 
to a species which was itself imperfectly described. This has made 
for much confusion in the case of the molesta-texana complex, which 
is at present so involved that no adequate solution seems possible. 
It is possible, however, to eliminate at least some of the difficulty and 
I justify the somewhat extensive discussion which follows on this 
ground. 

The molesta-texana tangle may be said to have begun in 1895, at 
which time Emery, acting on information from Pergande, shifted 
Say's Myrmica molesta to the genus Solenopsis. Prior to this, Emery 
had believed Say's species to be Monomorium pharaonis and it is 
abundantly clear that the change was made on other grounds than 
that of the original description. Emery's action necessitated the 
sinking of Mayr's name debilis (1886) and Buckley's exigua (1866) 
both of which became synonyms of molesta. In his preoccupation 
with this revisionary work Emery neglected to give any adequate de- 
scription of molesta, although in the same paper he set up the variety 
validiuscula as well as texana, which he regarded at that time as re- 
lated to pollux. In both cases recognition depended upon a com- 
parison with previously described forms. In the case of molesta, two 
of the three existing descriptions are worthless for this purpose and 
the third (Mayr's debilis) is scarcely detailed enough to permit the use 
of the fine distinctions which were necessary in this case. In 1901 
Forel gave texana specific status (without presenting a full description) 
and added to it the subspecies truncorum and carolinensis . In 1904 
Wheeler added the subspecies catalinae to texana and in 1908 he rec- 
ognized the variety castanea, which he attached to molesta. All four 
of these variants were set up by means of very brief comparisons to 
the species to which they were assigned. In the case of molesta one 
could refer to Mayr's original description of debilis but texana had 
never been described at all except in a roundabout, comparative 
fashion. It is no wonder that the character of the three forms as- 
signed to texana has remained enigmatical. 

In 1938 Dr. C. H. Kennedy described rosella. He dealt with all 
three castes in his description, figured them and noted how they differ 
from the corresponding caste in molesta. For the first time a species 
which had existed without adequate description since 1895 was put 
on a sound descriptive basis. For rosella is the insect that Emery, 



CREIGHTON: ANTS OF NORTH AMERICA 



Forel and Wheeler called texana. It is of course, necessary to sink 
rosella as a synonym of texana. I wish that this could be avoided for 
Dr. Kennedy's name is considerably more apt than texana. It stresses 
a color peculiarity of the female which is characteristic of this species. 
Moreover, texana is rare in Texas. It is much more abundant in the 
southeastern and central states and Emery was mistaken in supposing 
that this species is a representative of our southwestern ant fauna. 
In 1930 I had before me the types of carolinensis, truncorum and 
catalinae as well as specimens which Emery had pronounced identical 
with his texana. A study of these and much additional material has 
convinced me that several species have been lumped under texana. 
I believe that both carolinensis and truncorum are specifically dis- 
tinct. Although the worker of carolinensis is very similar to that of 
texana, the females of the two species are notably unlike. The eyes 
of the female of carolinensis are unusually large and occupy more 
than half the sides of' the head. Kennedy has pointed out that the 
eyes of the female of texana (rosella) are somewhat larger than those of 
molesta but the difference here is slight compared with the very large 
eyes of the carolinensis female. In the case of truncorum there are so 
many differences, even in the worker caste, that it is hard to see why 
Forel assigned it to texana. In truncorum the worker is larger, darker 
and more robust throughout, particularly the petiolar nodes, which 
are heavier and higher. The head is subquadrate rather than rec- 
tangular and the color is a very distinct, deep, castaneous brown. 
Finally, it is obvious that neither carolinensis nor truncorum should 
have been treated as subspecies of texana since all three occur in the 
same stations. Indeed Forel's two type series were both taken at 
Faisons. In the case of truncorum some additional observations are 
necessary. Wheeler redescribed this insect under the name castanea. 
I have compared the types of the two and find no differences by which 
they may be separated. I further cannot agree with Wheeler that 
there are intergrades which connect castanea with the western validi- 
uscula. Or perhaps I should say with the insect which Wheeler and 
I have called iialidiuscula, for Emery's original characterization of 
that subspecies is loose enough to apply to either validiuscula or 
truncorum. It may be that an examination of the types of validiuscula 
will show it to be the same as truncorum. If so, it will then be neces- 
sary to give a name to the form which has passed as validiuscula since 
1895. For this western subspecies of molesta, is in my opinion, per- 
fectly distinct and not to be confused with truncorum. For the above 
reasons I would arrange the molesta-texana complex as follows : 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

S. (Diplorhoptrum) carolinensis Forel 
" " molesta Say 

" " " subsp. validiuscula Emery 

" " texana Emery 

= rosella Kennedy 

" " " subsp. caialinae Wheeler 

" " truncorum Forel 

= castanea Wheeler 



9. SOLENOPSIS (DIPLORHOPTEUM) CAROLINENSIS Forel 

S. texana subsp. carolinensis Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 345 
(1901) 9 9 rf 1 . 

Type loc: Faisons, North Carolina. Types: M.C.Z. 

Range: North Carolina and Tennessee to southern New England. This insect 
appears to be considerably rarer and more sporadic in distribution than 
texana, which occurs in the same stations as carolinensis. 

S. carolinensis may be easily recognized if females are available for 
examination. The eyes of the female are much larger than those in 
related species. This difference is much more striking than the slight 
differences which distinguish the workers. 



10. SOLENOPSIS (DIPLOKHOPTRUM) KROCKOWI Wheeler 

S. krockowi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 428, pi. 26, 

figs. 28, 29 (1908) 9 9 . 
Type loc: Box Canyon, Sacramento Mts., New Mexico. Types: M.C.Z., 

Coll. W. S. Creighton. 
Range: southern New Mexico south into Chihuahua. 



11. SOLENOPSIS (DIPLORHOPTRUM) LONGICEPS M. R. Smith 

S. (D.) longiceps M. R. Smith, Proc. Ent. Soc. Wash., Vol. 44, p. 210 (1942)- 9 . 
Type loc: Hamilton County, Tennessee. Holotype: U.S.N.M., Paratypes: 

U.S.N.M. 
Range: Florida to Texas and north to the latitude of Tennessee. 

Despite the fact that longiceps is now known to have a rather ex- 
tensive range, the insect appears to be nowhere very abundant. Its 
rarity has largely kept it out of the hands of collectors and this has 
limited our knowledge of its distribution. Thus there are no records 



CREIGHTON: ANTS OF NORTH AMERICA Z6t 

at present to show the occurrence of longiceps in Alabama, although 
it must certainly be present in that state. 

12. SOLENOPSIS (DIPLORHOPTRUM) MOLESTA (Say) 

Myrmica molesta Say, Bost. Jour. Nat. Hist., Vol. 1, p. 293 (1836) 9 . 
Solenopsis molesta Emery, Zool. Jahrb. Syst., Vol. 8, p. 277 (1895) 9 9 cf . 
Myrmica minuta Say, Boston Jour. Nat, Hist., Vol. 1, p. 294 (1836) 9 . 
Myrmica exigua Buckley, Proc. Ent. Soe. Phila., Vol. 6, p. 342 (1866) 9 9 . 
S. fugax (part) Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 996 (1870) 9 . 
S. debilis Mayr, Ibid., Vol. 36, p. 461 (1886) 9 9 c? - 
Type loc: Indiana. Types: none known to exist. 
Range: eastern and central United States from the Gulf Coast into southern 

Canada. The insect is rare in the southern portions of the Gulf States, 

where it is replaced by several other small species. 

13. SOLENOPSIS (DIPLORHOPTRUM) MOLESTA VALIDIUSCULA Emery 

S. molesta var. validiuscula Emery, Zool. Jahrb. Syst., Vol. 8, p. 278 (1895) 9 ; 

Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 430 (1908) 9 . 
Type loc: San Jacinto and Los Angeles, California. Types: none in this 

country. 
Range: Pacific Coast states eastward to Colorado and New Mexico. 

14. SOLENOPSIS (DIPLORHOPTRUM) PERGANDEI Forel 

S. pergandei Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 343 (1901) 9 9 d 1 . 

S. (D.) pergandei M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 568, 

pi. 9, fig. 36 (1947 ) 9 . 

Type loc: Faisons, North Carolina. Types: none in this country. 
Range: southeastern United States as far north as Virginia. 



15. SOLENOPSIS (DIPLORHOPTRUM) PICTA Emery 

S. tennis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 262 (1886) 9 (nee 

S. tenuis Mayr 1877). 

S. picta Emery, Zool. Jahrb. Syst., Vol. 8, p. 278 (1895) 9 . 
-S. picta var. moerens Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 393 

(1915) 9. 

Type loc: Florida. Types: none in this country. 
Range: Gulf States from Florida to Texas. 

In my opinion Wheeler's variety moerens is a synonym of the typical 
picta. I have taken many colonies of this insect in southern Alabama 



z<5 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

and Mississippi, where it nests in hollow twigs of various kinds. In 
every series of any length there are always specimens which meet the 
color requirements of the typical picta and others which are dark like 
moerens. It is unfortunate that Wheeler should have chosen to give 
a name to the six specimens which formed the type series of moerens. 



16. SOLENOPSIS (DIPLOEHOPTRUM) PILOSULA Wheeler 

S. pilosula Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 426, pi. 26. 

figs. 26, 27 (1908) 9 cr". 

Type loo: Alice, Texas. Types: M.C.Z., Coll. W. S. Creighton. 
Range: known from type material only. 



17. SOLENOPSIS (DIPLORHOPTRUM) SALINA Wheeler 

S. salina Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 427, pi. 26, figs, 

24, 25 (1908) 9 . 

Type loe: Ft. Davis, Texas. Types: A.M.N.H., M.C.Z. 
Range: western Texas to California and south into Mexico. 



18. SOLENOPSIS (DIPLORHOPTRUM) TEXANA Emery 

S. pollux var. texana Emery, Zool. Jahrb. Syst. ,Vol. 8, p. 278 (1895) 9 . 

S. texana Porel, Ann. Soc. Ent. Belg., Vol. 45, p. 345 (1901). 

S. rosella Kennedy, Can. Entomol., Vol. 70, p. 232, pi. 19, figs. 1-11 (1938) 

9 9 cf . 

Type loc: Texas. Types: M.C.Z.? (see below). 
Range : central Texas to southern Ontario and the southeastern states. 

This insect is considerably more abundant in the southeastern states 
than in Texas. In the western part of Texas texana is very rare and it 
seems to be altogether absent from southern New Mexico and Ari- 
zona. For this reason it may be that Wheeler's subspecies catalinae will 
ultimately prove to be a separate species. There is so little material 
of catalinae known at present that its status is problematical and, for 
this reason, I have left it as a subspecies of texana. It may be noted 
here that Emery sent specimens of texana to WTieeler. These specimens 
were treated by Wheeler as cotypes. While there is no doubt that they 
were identified by Emery as texana, it is not certain that they are a 
part of the type series of that species. 



CREIGHTON: ANTS OF NORTH AMERICA 2oy 

19. SOLENOPSIS (DIPLORHOPTRUM) TEXANA CATALINAE Wheeler 

S. texana subsp. catalinae Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, 

p. 269 (1904) 9 9 . 

Type loc: Catalina Island, California. Types: M.C.Z. 
Range: known from type material only. 



20. SOLENOPSIS (DIPLORHOPTRUM) TRUNCORUM Forel 

S. texana subsp. truncorum Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 346 (1901) 

9 9. 
S. molesta var. castanea Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 430 

(1908) 9. 

Type loc: Faisons, North Carolina. Types: M.C.Z. 
Range: southeastern United States west to the Rockies. 

I have no hesitancy in treating castanea as a synonym of truncorum 
even though Wheeler had the types of the latter insect before him 
when he described castanea. At that time he noted that truncorum is 
"very similar to castanea but has a paler thorax". This very slight 
color difference was the basis for the recognition of castanea, yet 
Wheeler secured a false distinction by assigning castanea to molesta. 
Since Forel had assigned truncorum to texana it was natural to infer 
that the two differed in other ways than color. Actually they do not, 
and the very minor difference of color which distinguishes castanea 
is of no significance as a separatory character. The reasons for treat- 
ing truncorum as a species have been given in the discussion at the be- 
ginning of the subgenus Diplorhoptrum. 



Genus EpOECUS Emery 
(Plate 28, figures 1-3) 

The status of the genus Epoecus has been unsatisfactory from the 
outset. It was described in 1892 by Emery, who gave to the single 
species which represents Epoecus the name of its discoverer, Pergande. 
The material on which Emery based Epoecus was found by Pergande 
near Washington, D.C. It consisted of a series of males and females 
taken in a nest of Monomorium minimum. No workers of Epoecus 
were secured, a fact which led Emery to believe that the insect is a 
workerless parasite. On the other hand, the mixed nest contained 
not only workers of minimum but males and females of the "host" 
as well. Added to this unusual feature was the unexpected result 
which ensued when Pergande placed the mixed colony in a glass ob- 



Z4U BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

servation nest. The females of Epoecus attacked and killed the 
Monomorium males. This curious situation was known to Emery 
but he attempted no explanation for it. Subsequent observers have 
not hesitated to point out that the whole situation is decidedly ir- 
regular but there has been no opportunity to clarify it, since Epoecus 
has not been taken again. 

In addition to these unexplained ecological peculiarities, the 
taxonomic position of Epoecus is by no means above reproach. In 
the original description of the genus Emery related it to Anergates. 
This he did on the basis of similarities in the clypeus, mandibles and 
antennae of the two genera. At the same time he pointed out that the 
general appearance of the two insects was entirely different. In 1895 
Emery presented a somewhat more complete account of the structure 
of Epoecus. Here again he related the genus to Anergates on exactly 
the same morphological grounds as before. If one examines the de- 
scription given by Emery of the mandibular and clypeal structure of 
Epoecus his association is not easy to understand. The mandible of 
the female of Epoecus is described as tridentate. The clypeus is said 
to be impressed in the middle but armed on the anterior edge with 
two teeth. As the mandible of the female of Anergates bears a single, 
mucronate point and the clypeal border, while deeply incised, is en- 
tirely without teeth, it would appear that the only feature by which 
the two genera might be related is the three-jointed club of the anten- 
nal funiculus. Such a similarity is scarcely enough to offset the 
stril ing differences which separate the two insects. These differences 
made very little impression upon Emery who attempted to augment 
stn* :tural features with a similarity of habit. At the end of his second 
description of Epoecus, Emery cited Pergande's observation on the 
killing of the Monomorium males by the Epoecus females and, there- 
upon, added that the habits of Epoecus united it with Anergates! 
In 1921 the first Myrmicine section of the Genera Insectorum appeared. 
In it Emery united Epoecus and Anergates in a subtribe (Anergatini) 
of the tribe Monomoriini. His third description of Epoecus carried 
one interesting new observation. The gastric dorsum of the female 
was described as "sunken in the middle, at least in dried specimens" 
(enfoncee au milieu du moins dans les exemplaires desseches). How 
Emery could have overlooked such a significant character in his 
earlier work and why, after a quarter of a century, he suddenly dis- 
covered it, is not hard to explain. He needed further common char- 
acters to bolster the relationship between Anergates and Epoecus. 

In the opinion of the writer there is scant basis for Emery's view. 
Very fortunately there is a part of the type series of Epoecus in this 
country. The females which I examined show no gastric sulcus nor, 



CREIGHTON: ANTS OF NORTH AMERICA z4i 

for that matter, does the insect which Emery figured in 1895. The 
outstanding peculiarity of Epoecus is, as Emery noted, the strong 
similarity of the two sexes. The general body form is so nearly iden- 
tical that it is difficult to tell the sex unless one examines the genitalia. 
This is a most unusual condition for an ant and one which is simply 
not comparable to the situation in Anergates. As far as the structure 
of the male is concerned there would seem to be no reason whatever 
for associating the two genera. It is to be hoped that future work 
will bring to light additional data on Epoecus. Only when we are 
better acquainted with this insect can there be much hope of clari- 
fying its present unsatisfactory status. 



1. EPOECUS PEKGANDEI Emery 

E. pergandd Emery, Ann. Soc. Ent. Fr., Vol. 61, p. 276 (1892) 9 d 1 ; Emery, 
Zool. Jahrb. Syst., Vol. 8, p. 273, pi. 8, fig. 11, 12 (1895) 9 <?; Wheeler, 
Ants, Columbia Univ. Press, p. 498 (1910) 9 cf; M. R. Smith, Amer. 
Mid. Naturalist, Vol. 37, No. 3, p. 569, pi. 10, figs. 37, a (1947) 9 . 

Type loc: Washington, D.C. Types: U.S.N.M., A.M.N.H., M.C.Z. 

Range: known only from type material. 



Genus ANERGATES Forel 
(Plate 29, figures 1-3) 

In 1934 I described, as a new species, a single winged female of the 
genus Anergates which had been taken in flight near Englewood, New 
Jersey. Since that time a number of other specimens of Anergates 
have been secured in the northeastern United States and an examina- 
tion of some of this material has convinced me that Dr. Smith is cor- 
rect in regarding my species friedlandi as no more than a variant of 
the European atratulus. Although the two insects are by no means 
identical, several of the differences which I cited for friedlandi have 
proven too variable to be suitable for separatory characters. There 
are, on the other hand, certain minor differences between the Ameri- 
can and European specimens which seem quite constant. If there 
were no question concerning the geographical status of the American 
material, it would be in accord with many other such cases to treat 
friedlandi as a subspecies of atratulus. I find it unsatisfactory to at- 
tempt to treat friedlandi as a subspecies as long as there is any possi- 
bility that this insect may have been imported. In my opinion this 
possibility is too remote for reasonable acceptance but as others do 
not share this view I have preferred to accede to Dr. Smith's treat- 



242 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

ment offriedlandi as an insignificant variation of atratulus. I believe, 
however, that there is a very strong probability that it will later prove 
to be a North American subspecies of that form. 

This extraordinary workerless parasite was first described by 
Schenck in 1852. This observer was also the first to publish on the 
habits of Anergates. It would be hard to imagine a more remarkable 
set of structural modifications than those which occur in both sexes 
of atratulus. The virgin female possesses a deep, median sulcus on the 
dorsum of the gaster. After fertilization the excessive development of 
the ovaries separates the gastric sclerites and stretches the inter- 
segmental membranes between them. The lateral expansion is greater 
than the dorso-ventral stretching, with the result that the gaster of 
the fertile female finally assumes a shape rather like a biscuit. The 
separated sclerites appear like islands on the top and bottom surfaces. 
The structure of the male is even more aberrant. This sex is apterous 
and pupoidal. The body apparently never becomes fully chitinized. 
The gaster is curved under at the tip and provided with a dispro- 
portionally large set of genitalia. In both sexes the mandibles are 
poorly developed and apparently quite useless for purposes of feed- 
ing. It is no wonder that this insect has attracted much interest or 
that, despite its rarity, its habits have been repeatedly studied. 
While the significance of some of the observations is not altogether 
clear, there is good general agreement as to the behavior of this re- 
markable species. Anergates is a parasite of Tetramorium caespitum. 
At maturity a parasitized nest consists of a single fertile female of 
Anergates, a considerable number of caespitum workers and a large 
number of pupoidal males and virgin females of Anergates. The 
caespitum workers feed and care for the parasites but are particularly 
attentive to the males and much less interested in the females, (Adlerz 
1913, Wasmann 1908). It was shown by Janet (1897) that the male 
of Anergates possesses unusually large mandibular glands and Forel 
(1922) supposes that the secretion from these glands is relished by 
the caespitum workers. Because the Anergates male is apterous, the 
nuptial flight has undergone some peculiar modifications. Copula- 
tion takes place between sisters and brothers (adelphogamy) within 
the confines of the nest. Mating is difficult for the clumsy, pupoidal 
male and is facilitated, as Forel has pointed out, (1922) by the docility 
of the female. After fertilization the female emerges from the nest 
for the nuptial flight. It is obvious that at the completion of the 
nuptial flight the Anergates female must find a nest of T. caespitum 
and gain access to it. Repeated experiments have been performed to 
ascertain how this is accomplished but the results have been uncertain 
in most cases. It is easy to show that the fertilized Anergates female 



CREIGHTON: ANTS OF NORTH AMERICA 24o 

will try to gain access to the caespitum nest. This she does by making 
an unobserved entry or, in many cases, by seizing the antenna of a 
caespitum worker who thereupon drags her into the nest. What 
follows next is not so clear. In the great majority of cases the Aner- 
gates female is killed by the caespitum workers if we may judge from 
experimental data. In one case, however, there has been a different 
result. In 1912 Crawley succeeded in getting a colony of Tetramorium 
to accept an Anergates female. This colony contained sexual forms 
of the host. At the end of a week following the introduction of the 
Anergates female to the nest, the caespitum workers had killed and 
cut to pieces the caespitum males and females. The introduced female 
of Anergates later showed the characteristic gastric enlargement 
which marks the mature queen but died without having laid any 
eggs. In summing up the evidence concerning this and other experi- 
ments Donisthorpe (1915) expressed the opinion that the destruction 
of the Tetramorium female by her own workers is probably the nor- 
mal sequence of events following the entrance of the Anergates fe- 
male into a caespitum colony. It is difficult to see how else the caes- 
pitum female could be eliminated, since it is unlikely that the Aner- 
gates female could kill her. 



1. ANERGATES ATRATULUS (Schenck) 

Myrmica atratulus Schenck, Jahrb. Ver. Nassau, Vol. 8, p. 91 (1852) 9 . 

A. atratulus Forel, Fourmis Suisse, p. 68, pi. 2, figs. 28, 29 (1874) 9 cf ; E. 

Andre, Spec. Hym. Europe, Vol. 2, p. 278, pi. 16, figs. 18, 19, pi. 18, 

figs. 1-6 (1882) 9 cf ; Adlerz, Bih. Svenska Vet. Akad. Handl., Vol. 11, 

No. 18, p. 274, pi. 3, figs. 1-9 (1886) 9 cf ; Wheeler, Ants, Columbia Univ. 

Press, p. 498, fig. 279 (1910) 9 cf ; Donisthorpe, British Ants, p. 89, pi. 6 

(1915) 9 cf ; Forel, Fauna Ins. Helvet. Hym. Form., p. 17 (1915) 9 cf ; 

Emery, Bull. Soc. Ent. ItaL, Vol. 47, p. 168, fig. 44 (1916) 9 cf ; M. R. 

Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 570, pi. 10, figs. 38, 38a 

(1947) 9. 
Tetramorium atratulum Mayr, Verh. Zool.- hot. Ges. Wien, Vol. 5, p. 249 

(1855) 9. 
Tomognathus atratulus Mayr, Europ. Formicid., p. 56 (1861) 9 ; Schenck, 

Jahrb. Ver. Nat. Nassau, Vol. 16, p. 164 (1861) 9 cf . 
Anergates friedlandi Creighton, Psyche, Vol. 41, No. 4, p. 193 (1934) 9. 
Type loc: Nassau, Germany. Types: none in this country. 
Range: (in the United States) Connecticut to northern Virginia. 
Host: Tetramorium caespitum. 

It seems advisable to note here the characters in which the Ameri- 
can material of Anergates differs from that taken in Europe. In the 



244 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

American specimens the mandible bears a much longer mucronate 
tooth or point; the eyes are smaller, more nearly circular, more strongly 
convex and with somewhat smaller facets; the lateral portions of the 
pronotum are more concave and blunter behind, so that when seen 
from the side they are quadrangular in outline; the gastric sculpture 
is heavier, with most of the upper surface of the gaster opaque. 
These differences hold for all the American specimens which the 
writer has seen. 

The presence of Anergates in North America has an important 
bearing on the geographical status of its host, Tetramorium caespitum. 
I have shown elsewhere that there is no reason why caespitum may 
not be considered a native North American species. This probability 
becomes a virtual certainty in view of the presence of Anergates in 
this country. I may say at the outset that I do not doubt that caes- 
pitum could be introduced from Europe. It is likely that the insect 
has been brought into this country many times, perhaps even by the 
early colonists. But I cannot agree that the first advent of caespitum 
on this continent is a result of importation. To do so implies that 
Anergates has also been imported. I believe that it can be demon- 
strated that the probability for this having occurred is too remote to 
be credible. 

It may simplify matters to consider first the conditions which at- 
tend the introduction of a free-living species. In general there are 
three critical factors involved. The insect must be sufficiently abun- 
dant in its home territory to make its chance inclusion in cargoes an 
easy matter. It must have the ability to endure the difficulties in- 
volved in transportation. It must find an area at the end of its voy- 
age where the conditions are not widely dissimilar to those to which 
it has become accustomed. The nest-founding reactions of the or- 
dinary female ant are ideally adapted to make it a successful stow- 
away. After fertilization the female usually seeks a protected spot 
and remains in it for a considerable period. Her self-effacing tactics 
make discovery difficult, and the transported female is likely to end 
her voyage in excellent shape. Since the female ant is such a good 
traveller, the hazards attendant on introduction are considerably re- 
duced in her case. If the species is abundant in its native habitat and 
if transportation takes it to a climatically similar region, there is 
every reason to expect that successful introduction may ensue. In- 
deed, the chances are so good that it is difficult to explain why so 
few ants have been introduced into this country from Europe. 

The entire situation changes radically in the case of a parasitic 
species such as Anergates. In the first place, the incidence of Aner- 
gates in Europe is exceedingly low. It is one of the rarest of Euro- 



CREIGHTON: ANTS OF NORTH AMERICA Z4o 

pean ants, and the chance for its accidental inclusion in a cargo is 
remote. In the second place, the nest-founding reactions of the Aner- 
gates female are unfavorable for purposes of transportation. The in- 
sect does not seek a secluded spot after fertilization, but becomes ac- 
tive in searching out colonies of the host, to which it must promptly 
gain admission if it is to survive. Not only is it unlikely that a single, 
fertilized female could be included in a cargo but it is even more un- 
likely that it could survive if this happened. That such a female 
could be disembarked at the end of the voyage and then discover 
and parasitize a nest of the host is plainly incredible. Those who 
wish to believe that Anergates has been introduced into the United 
States must assume, therefore, that the introduction involved the 
transportation of a parasitized nest of the host, caespitum. As may be 
seen, this is a much more difficult matter than the shipment of a single 
fertilized female. For the nest must not only have survived the voy- 
age but it must have been reestablished intact at the end of it. Fur- 
thermore, this reestablishment must have occurred in an area where 
there was an abundant population of the host already present. I do 
not say that it is impossible for such a thing to have happened. I do 
say that every probability is dead against it. If Anergates has man- 
aged to accomplish this miracle, it has been favored with the most 
stupendous piece of luck that any parasitic species ever enjoyed. A 
much more reasonable view is that Anergates reached North America 
as a result of natural means of dispersal. If so, its host, Tetramorium 
caespitum, must have acted in the same way. In my opinion, there- 
fore, the presence of Anergates on this continent constitutes sufficient 
evidence to permit us to treat Tetramorium caespitum as a native North 
American ant. 



Genus EREBOMYRMA Wheeler 
(Plate 30, figures 1-5) 

As far as the writer has been able to determine, there have been no 
additional records published for Erebomyrma longi since its descrip- 
tion by Wheeler in 1903. This is unfortunate, since we know very 
little about the biology of this insect, and there are indications that 
its habits would repay careful observation. Erebomyrma is closely 
related to several other genera (Oligomyrmex, Carebara, etc.) which 
are known to be lestobiotic in the nests of termites or other ants. It 
has been assumed that this relationship is also true of Erebomyrma. 
While there is no reason to doubt that Erebomyrma is lestobiotic, it 
should be remembered that the principal evidence for this supposi- 



Z4b BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

tion has been derived from the structural similarities between this 
genus and the others mentioned above. 

In size, coloration and general body form the worker of longi 
closely resembles that of Solenopsis molesta. With proper magnifica- 
tion, however, a number of significant differences may be readily 
seen. The antennae are eleven-jointed in longi, with the extra joint 
occurring in the series of small segments which separate the first 
funicular joint from the two-jointed club. In addition, the epinotum 
is armed with two short, erect teeth and is densely rugose-reticulate. 
This sculpture is also present on the mesopleurae and the base of the 
petiole. The female of longi also possesses eleven-jointed antennae. 
This, of course, will not distinguish it from the Solenopsis female, in 
which the number of antennal joints is eleven (except in the subgenus 
Diagyne) . The longi female is not apt to be confused with Solenopsis 
because of its heavy sculpture, short antennal scapes, dentate epino- 
tum and the peculiar shape of the postpetiole, which has a concave 
anterior face and a strongly convex posterior face when seen from 
above. The male of Erebomyrma has thirteen-jointed antenna, one 
more joint than is present in the male of Solenopsis. In addition the 
Erebomyrma male is more heavily sculptured than is generally the 
case with those of Solenopsis and its postpetiole is extensively fused 
with the gaster over its entire posterior face. 



1. EREBOMYRMA LONGI Wheeler 

E. longi Wheeler, Biol. Bull., Vol. 4, p. 140, figs. 1-5 (1903) 9 9 d" ; Wheeler, 
Ants, Columbia Univ. Press, p. 428, figs. 257 a-e (1910) 9 ? d 1 ; M. R. 
Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 571, pi. 11, fig. 39 
(1947) 9. 

Type loc: Denton, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 

Range: known only from type material. 



Genus MYRMECINA Curtis 
(Plate 31, figures 1-5) 

The genus Myrmecina is divisible into two components which are 
marked by widely different geographical characteristics. The larger 
group consists of those species whose distribution extends from south- 
eastern Asia through the East Indies and Oceania into northern 
Australia. The second and smaller group comprises the holarctic 
representatives which occur in Europe, northern Asia and the United 
States. The taxonomic development of the two groups has been en- 



CREIGHTON: ANTS OF NORTH AMERICA JAI 

tirely different. There has been practically no specific subdivision in 
the case of the paleotropical forms, while the holarctic representa- 
tives have been consistently lumped under a single species, gramini- 
cola. This practice has not always led to satisfactory results. In 
1915 Emery proposed to separate sicula, long regarded as a variety 
of graminicola, as a distinct species. This change was made on the 
basis of the unarmed clypeus of sicula, which lacks the three teeth 
characteristic of the typical graminicola. It happens that the three 
representatives of Myrmecina which occur in North America have 
the clypeal teeth reduced to a degree which would relate them to 
sicula rather than to graminicola. There is no need to make such a 
shift of relationship, since there is a much better alternative. If sicula 
deserves to be regarded as specifically distinct, our three forms may 
also be considered as variants of a separate species. This is the plan 
which I propose to follow in the present work. Of these three forms, 
two, americana and the subspecies bremspinosa, were described by 
Emery in 1895. The third variant, the subspecies texana, was set up 
by Wheeler in 1908. The following discussion will deal mainly with 
americana and bremspinosa, since texana is known only from a small 
series of types. 

When Emery described americana and bremspinosa he was depen- 
dent upon material coming from the northeastern United States. As 
I shall presently show, the situation in this area is an exceptionally 
difficult one to analyze as far as the genus Myrmecina is concerned. 
Emery based his distinction on three points. His americana was 
larger, darker and had longer epinotal spines than bremspinosa. The 
color diagnostic is very unsatisfactory and generally inapplicable but 
the other criteria deserve careful consideration. The large individuals 
with long and slightly upturned epinotal spines which come from the 
northeastern United States show, in addition to these features, a 
strong cephalic sculpture consisting of wavy longitudinal rugae and 
a broad, V-shaped impression in the occipital border. Individuals 
with these characteristics are commonly met with from New England 
south to Washington but in more southern areas they tend to occur 
in the Appalachian highlands at considerable elevations. The smaller 
individuals with short spines which come from the New England and 
Atlantic states are decidedly variable as to the degree of development 
of the cephalic rugae and also as to the occipital impression. As one 
goes west, however, this variability gives way to a condition in which 
the head is finely punctate with the longitudinal rugae very feeble in 
the middle and clearly visible only at the sides. In addition, the occi- 
pital emargination is much more feeble. This is the form which occurs 
from Texas to Arizona. Unless I am very much mistaken, Emery's 



248 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

brevispinosa is actually an intergrade between the small and rather 
smooth western subspecies and the larger, heavily sculptured eastern 
form. It is true that the area of intergradation of the two is much 
more extensive than is usually the case. Indeed, this area of inter- 
gradation appears to extend all along the base of the Appalachians 
and as far west as the Mississippi. At the same time, each subspecies 
occupies a separate range, although in the case of the eastern race the 
separation is more a matter of elevation than latitude. In order to 
overcome the difficulty of dealing with a name attached to an inter- 
grade, I propose to expand Emery's definition of brevispinosa to in- 
clude the characteristics of the western specimens. This practice has 
already been sanctioned by other myrmecologists who have generally 
regarded the western specimens as representing the 'typical' brevi- 
spinosa. 

The nests of americana and brevispinosa are small and obscure. 
There are rarely more than one hundred individuals in a colony. The 
nests are usually built in moist, shady areas, often under small stones. 
The insects are very timid and feign death when disturbed. Forel 
claims that the European graminicola has a faint odor suggestive of 
raspberries. To the writer the odor of a living colony of americana re- 
sembles camphor, although it may be admitted that I have never 
found anyone else who thought so. 



Key to the subspecies of Myrmecina americana Emery 

1. Base of the first gastric segment finely punctate and subopaque 

americana subsp. texana 

Base of the first gastric segment smooth and shining, the sculpture con- 
sisting of scattered piligerous punctures '. 

2. Epinotal spines long and usually turned upward at their tips; cephalic 
rugae heavy; occipital border with a pronounced median impression; 

length 3.5 mm americana 

Epinotal spines short and dentiform; cephalic rugae weak, often absent at 
the middle of the head; occipital border feebly impressed; length 2.5 mm. 

americana subsp. brevispinosa 



1. MYRMECINA AMERICANA Emery 

M. latreille Mayr, Verh. Zool-bot. Ges. Wien., Vol. 36, p. 455 (1886) 9 , (nee 

latreille Curtis). 

M. latreille subsp. americana Emery, Zool. Jahrb. Syst., Vol. 8, p. 271 (1895) 9 . 
M. graminicola subsp. americana M. R. Smith, Amer. Mid. Naturalist, Vol. 

37, No. 3, p. 572, pi. 11, fig. 40 (1947) 9 . 



CREIGHTON: ANTS OF NOKTH AMERICA Z4y 

M. graminicola subsp. qiiadrispina, Enzmann, Jour. N. Y. Ent. Soc., Vol. 54, 
No. 1, p. 13, figs. 1, 2 (1946) 9 . 

Type loc: District of Columbia. Types: U.S.N.M., M.C.Z. 

Range: southern New England west to Iowa and south to the highlands of 
northern Georgia and Alabama. In the southern part of its range the in- 
sect occurs at elevations of 2000 feet or more. 

The insect which Enzmann has recently described as Myrmecina 
graminicola subsp. quadrispina is quite obviously a synonym of 
americana. It is difficult to understand how such a mistake could 
have occurred, for not only are there type specimens of americana 
present in American collections but, in addition, Emery's original 
description of americana embodies most of the points which Enzmann 
cited as the definitive criteria of quadrispina. Thus Emery stated that 
a rudimentary clypeal tooth is present in americana and that its epino- 
tal spines are approximately as long as their bases are wide, pointed 
and notably thin at the tips which are curved outward and upward. 
Since the types of americana came from the District of Columbia, 
there is no reason why Enzmann should have chosen to regard speci- 
mens with short, straight spines which came from Texas and Ari- 
zona as representatives of americana. These specimens are referable 
to the subspecies bremspinosa. Although the length of the epinotal 
spines varies considerably in bremspinosa it shows certain sculptural 
peculiarities which distinguish it from the typical americana. It is 
instructive to note that Enzmann has cited some of these sculptural 
features as characteristic of 'americana.' In 1941 Buren suggested 
that americana probably deserved full specific rank. Since he did 
not act on this eminently sound suggestion it has remained for the 
writer to put it into practice. 



2. MYRMECINA AMERICANA BREVISPINOSA Emery 

M. latreille subsp. americana var. bremspinosa Emery, Zool. Jahrb. Syst., 

Vol. 8, p. 271 (1895) 9 9 cf . 

Type loc: District of Columbia. Types: U.S.N.M., M.C.Z. 
Range: southeastern United States west to Arizona and north through the 

Piedmont as far as southern New York. 

As has been shown elsewhere it is virtually certain that the types 
of bremspinosa are intergrades between the two races of americana 
which occur in the eastern United States. While the northern race is 
correctly designated as the typical americana the southern race, 
which exhibits its most characteristic condition in the southwestern 
states, has no name unless we expand the definition of bremspinosa 



zoU BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

to include the western specimens. It seems much better to do so than 
to become involved in the difficulties which are certain to arise if the 
name brevispinosa is discarded. It should be remembered, however, 
that under this plan the characteristics of brevispinosa will be more 
extreme than those cited by Emery. 

3. MYEMECINA AMERICANA TEXANA Wheeler 

M. graminicola subsp. texana Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, 

p. 422 (1908) 9 . 

Type loc: Shoal Creek, Austin, Texas. Types: M.C.Z. 
Range: known only from western Texas. 

The status of this insect cannot be certainly determined until we 
know more about its range. Since it appears to occur in the middle of 
the range of brevispinosa, it is very unlikely that it is a geographical 
race of americana. When more material is available for examination, 
texana will probably prove to be a separate species, for it has rather 
distinct structural features which separate it from americana. Since 
so little is known about it at present, it seems best to retain it pro- 
visionally as a subspecies of americana. 



Genus MACROMISCHA Roger 
(Plate 32, figures 1-3) 

The three species of this beautiful genus which occur in the United 
States are all closely related to other species whose range lies further 
to the south. As Dr. M. R. Smith pointed out in 1939, fioridanus is 
strikingly similar to the Bahaman species M. allardycei. A similar 
relationship connects the Texan species subditiva to laevissima of 
Mexico, while polita, which occurs in southern Arizona, shows struc- 
tural affinities with flavitarsus of Guatemala. At present it seems en- 
tirely satisfactory to treat our three representatives as separate 
species but the possibility should be borne in mind that, when the 
genus Macromischa is more carefully studied, it may be necessary to 
reduce one or all of them to subspecific rank. 

It has now been shown that the three subgenera which Mann pro- 
posed for Macromischa in 1920 are indefensible. As a result, the genus 
must be treated as a single taxonomic unit. It is unfortunate that 
this view, which rests upon evidence of the strongest character, should 
have been obscured by Wheeler's refusal to abandon the older plan. 
Wheeler not only championed Mann's subgenera but at one time he 



CREIGHTON: ANTS or NORTH AMERICA /ol 

proposed that they be given generic rank. This proposal, which ap- 
peared in 1931, was made without any reference to additional facts 
which might have supported the elevation. In this same year Dr. 
C. G. Aguayo published evidence that makes it impossible to separate 
Macromischa and Croesomyrmex even on a subgeneric basis. Dr. 
Aguayo had discovered a new subspecies of wheeleri (the subgenotype 
of Croesomyrmex) that has short but distinct epinotal spines. This 
is the characteristic that supposedly distinguishes Macromischa from 
Croesomyrmex. Five years later Dr. M. R. Smith discovered a paral- 
lel situation in the case of the Puerto Rican species isabellae. Here 
the typical form belongs to Macromischa, for it has well-developed 
epinotal spines. But Dr. Smith's subspecies mutica lacks epinotal 
spines and, as a result, it would have to be placed in the subgenus 
Croesomyrmex. It is astonishing that Wheeler persisted in holding 
out for the validity of the subgenera of Macromischa in the face of 
this evidence (1937). It is difficult to see how anyone would be will- 
ing to accept the situation in which a species would have to be split 
between two subgenera. The writer fully agrees with Dr. Smith that 
the subgenera of Macromischa are indefensible as defined at present. 
Until better separatory characters can be found, it is imperative that 
this genus be treated as a single unit. The following key is that pre- 
sented by Dr. Smith in 1939. 

Key to the species of Macromischa 

1. Antennal scape robust, short, not quite reaching half way between the eye 
and the posterior border of the head; sculpturing of the head, thorax, 
petiole and postpetiole rugose-reticulate; eye with unusually large facets; 

color yellow to yellowish brown floridanus 

Antennal scape slender and extending further posteriorly; sculpturing not 
as above; eye with smaller facets 2 

2. Peduncle of the petiole at least twice the length of the petiolar node; the 
latter short; pilosity of the scape closely appressed; color light brown to 

piceous brown subditiva 

Peduncle of the petiole no longer than the length of the petiolar node, the 
latter long; pilosity of the scape suberect; color blackish polita 



1. MACROMISCHA FLOKIDANUS Wheeler 

M . floridanus Wheeler, Bull. Mus. Comp. Zool. Harvard, Vol. 72, p. 27 (1931) 
9 ; M. R. Smith, Ann. Ent. Soc. Amer., Vol. 32, No. 3, p. 507, fig. Ic 
(1939) 9. 

Type loc: Paradise Key, Dade Co., Florida. Types: M.C.Z., U.S.N.M., 
Coll. W. S. Creighton. 

Range: known only from type material. 



vjv/ BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The nest of the type series of floridanus was found in the hollow 
branch of a small tree. It is evidently arboreal, hence Wheeler's 
original assignment of this species to the supposedly terricolous sub- 
genus Antillaemyrmex is a further evidence of the impossibility of 
attempting to separate Macromischa into satisfactory subgenera. 

2. MACROMISCHA POLITA M. R. Smith 

M. polita M. R. Smith, Ann. Ent. Soc. Amer., Vol. 32, No. 3, p. 506, fig. Ib 

(1939) 9. 
Type loc: Tucson area, Phoenix, Florence, Arizona. Types: U.S.N.M., 

A.M.N.H. 
Range: central and southern Arizona. 

Although a single nest of polita was found under the bark of a cot- 
tonwood tree, most of the specimens belonging to this species have 
been taken on the ground. There is little to indicate that it is arboreal. 

3. MACROMISCHA SUBDITIVA Wheeler 

M. subditiva Wheeler, Psyche, Vol. 10, p. 99, fig. 5 (1903) 9 ; Mann, Bull. 

Amer. Mus. Nat. Hist., Vol. 42, No. 8, p. 409 (1920) 9 ; M. R. Smith, 

Ann. Ent. Soc. Amer., Vol. 32, No. 3, p. 503, fig. la (1939) 9 9 a"; M. R. 

Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 572, pi. 11, fig. 41 

(1947) 9. 
Type loc: worker, Walnut Creek, Austin and New Braunfels, Texas; female 

and male, Victoria, Texas. Types: worker, M.C.Z.; female and male, 

U.S.N.M. 
Range: central Texas from Austin south to the Brownsville region. 

The range of this species undoubtedly extends into northeastern 
Mexico, although to date there seem to be no records from areas south 
of the border. M. subditiva may be arboreal but data on this point is 
inconclusive. It has been taken from nests under willow bark and 
from dead, hollow branches lying on the ground. 



Genus LiEPTOTHORAX Mayr 
(Plate 33, figures 1-4) 

The revisionary steps which established the subgenera of Lepto- 
thorax were begun toward the end of the last century. By 1915 the 
present five subgenera had been set up and since that time no further 
change has been accepted. This stability is remarkable in view of the 



CEEIGHTON: ANTS OF NORTH AMERICA zoo 

fact that two of the groups are structurally heterogeneous. The sub- 
genera Goniothorax and Leptothorax include some species with 
eleven-jointed antennae and others in which the antennae have 
twelve joints. In most ant genera the number of funicular joints is 
constant. Conversely, a funicular organization which involves a dif- 
ferent number of joints is usually accompanied by other significant 
structural peculiarities. The prevalence of such conditions has given 
rise to the belief that in myrmecology the number of antennal joints 
is an important generic or subgeneric criterion. The radical departure 
from this stand in the case of the subgenera of Leptothorax merits 
careful consideration. It has given rise to confusion in the past and this 
confusion has not been limited to the novice. 

Although the subgenera of Leptothorax were delimited by several 
workers, the outstanding contribution to the constitution of this genus 
was made by Carlo Emery. In 1915 he published a scheme which em- 
bodied the basic subgeneric distinctions at present employed. Emery 
was fully aware of his heterodox views concerning the subgenera 
Leptothorax and Goniothorax and was at some pains to explain his 
position. It may be added that in the face of subsequent criticism 
Emery stuck to his guns with such pertinacity that as yet no one has 
dared to propose a better system. Yet Emery's views, while generally 
accepted, are far from satisfactory. Emery based his contentions 
primarily on the venation of the winged sexes. In the subgenera 
Mychothorax and Dichothorax the radial cell is long and open. In 
the subgenera Leptothorax, Goniothorax and Temnothorax the radial 
cell is short and closed. A further consideration of the last group of 
subgenera gave another venational distinction. The presence of a 
discoidal cell in the subgenera Leptothorax and Temnothorax dis- 
tinguished these groups from Goniothorax, in which the discoidal 
cell is absent. So far Emery's position is easily defensible, if one is 
prepared to accept the proposition that the venation of the various 
groups is constant. In the subgenera Leptothorax and Temnothorax, 
however, the venation is identical. In separating these two groups 
Emery relied upon differences in the body hairs and the presence or 
absence of the mesoepinotal suture in the worker. Since both these 
characters show intergrading conditions, it is not clear why Emery 
championed their significance while denying equal significance to the 
clear-cut, non-intergrading character of the number of antennal 
joints. Yet Emery was very positive on this score. When Wheeler 
and Forel separately proposed to delete from Goniothorax those 
species having eleven-jointed antennae (the subgenus Nesomyrmex 
Wheeler or Caulomyrma Forel) Emery denied the validity of the pro- 
posal. It is difficult to escape the impression that Emery, despite the 



ZtA BULLETIN: MUSEUM OP COMPARATIVE ZOOOLGY 

evidence which he accumulated to prove his point, was actually ex- 
erting the taxonomist's prerogative and basing his subgenera on gen- 
eral structural similarities which are more easily seen than described. 
If so, he was largely justified. The majority of the species which 
Emery included in the subgenus Leptothorax are, despite the differ- 
ence in the number of antennal joints, obviously of close relationship. 
Yet the matter of the funicular variation has been a serious stumbling- 
block in the taxonomy of the group. It undoubtedly worried Emery 
himself, since he regarded the species having eleven-jointed antennae 
as "exceptional". This is true enough if one is dealing with the Old 
World representatives. There is but one species, the Mediterranean 
flavicornis, which shows the "exceptional" condition against sixty- 
eight species in which the antennae are twelve-jointed. In the North 
American species, however, the situation is different. More than a 
third of the New World species in the subgenus Leptothorax possess 
eleven-jointed antennae. It may be doubted that the student of North 
American ants will consider a condition which he finds in every third 
species of Leptothorax as "exceptional". He must learn to evaluate 
existing generic keys, particularly that published by Wheeler in 1922. 
This key failed to take account of the variable number of antennal 
joints in the subgenus Leptothorax. The number is given as twelve, 
hence all members of the subgenus Leptothorax which have eleven- 
jointed antennae will key out to the subgenus Mychothorax. Per- 
haps this is less of a misfortune than might appear at first sight. At 
least the writer has been unable to see that the mesoepinotal suture 
of the worker in Mychothorax is a suitable character for a major key 
split. In the key which is presented in the following pages no at- 
tempt has been made to separate the subgenera. The important part 
played by the sexual forms of Leptothorax in subgeneric delimitation 
seriously limits the possibility of making such distinctions in a key 
based entirely on worker characteristics. 

Because of their inconspicuous habits and the small size of their 
colonies, the ants of the genus Leptothorax may be easily overlooked. 
They are, nevertheless, an exceedingly interesting group and one which 
is ideal for laboratory study because of the ease with which they 
adapt themselves to artificial nests. This adaptability is probably an 
outcome of the fact that many of the species nest by choice in pre- 
formed cavities. They may be found nesting in crannies beneath 
rock chips which have flaked from the tops of ledges, in cavities in 
and under bark, in hollow twigs, in dried grass stems, in old galls and 
in empty nut shells. Most of the species will, on occasion, nest in the 
soil and some do so as a matter of preference. There also seems to be 
a notable tendency for these insects to build their nests so that they 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Key to the species of Leptothorax 

1. Petiole and postpetiole armed with spine-like protuberances; humeri of 

the pronotum distinctly angular (Subgenus Goniothorax) wilda 

Petiole and postpetiole without spine-like protuberances; humeri of the 
pronotum rounded or indistinctly angular 2 

2. Antennae twelve jointed 3 

Antennae eleven jointed 20 

3. Antennal scapes surpassing the occipital margin; dorsum of the promeso- 
notum strongly convex in profile; mesoepinotal suture profoundly im- 
pressed (Subgenus Dichothorax) 4 

Antennal scapes not surpassing the occipital margin; dorsum of the pro- 
mesonotum flat or feebly convex in profile; mesoepinotal suture at most 
with a shallow impression 5 

4. Node of the petiole, seen in profile, low and angular, seen from behind 
the crest of the node is flat or with a shallow concave impression; color 

piceous brown pergandei 

Node of the petiole, seen in profile, with a blunt and rounded crest, seen 
from behind the crest of the node is slightly convex; color variable, 
piceous brown to yellow pergandei subsp. fioridanus 

5. Base of the first gastric segment reticulo-punctate silvestrii 

Base of the first gastric segment smooth and shining 6 

6. Dorsum of the thorax very smooth and highly shining, entirely devoid of 
sculpture except for small and widely spaced piligerous punctures 

schmitti 

Dorsum of the thorax variously sculptured, never entirely smooth and 
shining 7 

7. Dorsum of the postpetiole coarsely reticulo-rugose texanus 

Dorsum of the postpetiole punctate or granulose but not reticulo-rugose; 
rugae, if present, longitudinal and confined to the sides of the node .... 8 

8. Posterior half of the head in large part smooth and shining with a broad 
central strip which is free from sculpture extending forward to the an- 
tennal lobes 9 

Head largely or entirely sculptured, the surface feebly shining or com- 
pletely opaque 10 

9. The antennal scape in repose failing to reach the occipital margin by an 

amount not exceeding its greatest thickness nitens 

The antennal scape in repose failing to reach the occipital margin by an 
amount at least twice as great as its greatest thickness 

nilens subsp. heathi 

10. Head densely and evenly punctate, the punctures not interspersed with 
striae or rugae, the surface completely opaque; color pale yellow 

terrigena 

Head with striae or rugae as well as punctures, the surface usually feebly 
shining; color brownish yellow to dark brown 11 

11. Epinotal spines joined at their base by a distinct transverse ridge or 
welt which lies at the angle between the basal and declivious faces of the 



CKEIGHTON: ANTS OF NORTH AMERICA 



epinotum obturator 

Epinotal spines not joined at the base by a transverse welt 12 

12. Dorsum of the thorax densely and evenly punctate, rugae if present very 
feeble; sides of the thorax with heavy punctures which largely obscure 

the rugae 13 

Dorsum of the thorax with the punctures interrupted by prominent rugae 
on the epinotum and mesonotum and often on the pronotum as well; 
rugae on the sides of the thorax not obscured by punctures 16 

13. The antennal scape in repose failing to reach the occipital margin by an 
amount twice as great as its greatest thickness; epinotal spines reduced 

to short, stumpy angles andrei 

The antennal scape in repose failing to reach the occipital margin by an 
amount no greater than its greatest thickness; epinotal spines well- 
developed 14 

14. Sides of the petiole punctate only 15 

Sides of the petiole with rugae as well as dense punctures 

nevadensis subsp. melanderi 

15. Head (mandibles excluded) one-sixth longer than broad nevadensis 

Head (mandibles excluded) not more than one-eighth longer than broad 

nevadensis subsp. eldoradensis 

16. Node of the petiole with feeble rugae (in addition to the dense punctures) 

which do not break the even outline of the node furunculus 

Node of the petiole with very coarse rugae which give a rough outline to 
the node 17 

17. Postpetiole very voluminous, approximately twice as wide as the node of 

the petiole and half as wide as the gaster texanus subsp. davisi 

Postpetiole not twice as wide as the petiole and at most not more than 
one-third as wide as the gaster 18 

18. Dorsum of the thorax completely covered with coarse, longitudinal rugae 
except for a small, heavily punctured area on the mesonotum 

nevadensis subsp. rudis 

Rugae on the dorsum of the thorax largely confined to the epinotum and 
the rear of the mesonotum, the anterior portion of the thorax punctate 
only 19 

19. Epinotal spines short; the thoracic dorsum feebly shining . . . .tricarinatus 
Epinotal spines longer; the thoracic dorsum largely opaque 

tricarinatus subsp. neomexicanus 

20. Dorsum of the postpetiole shining, the sculpture consisting of widely 
spaced, small punctures with the surface between them smooth or deli- 
cately shagreened 21 

Dorsum of the postpetiole opaque or nearly so, the surface densely punc- 
tate or punctato-granulose 22 

21. Hairs of the scape fully erect; interrugal sculpture of the head heavy 

enough to dull the surface which is feebly shining provancheri 

Hairs of the scape reclinate; interrugal sculpture of the head more feeble, 
the surface moderately shining provancheri subsp. glacialis 

22. Antennal scapes with moderately abundant, erect hairs present on all 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



surfaces 

Antennal scapes with the hairs fully appressed or at most with a few 
suberect hairs confined to the anterior surface of the scape 24 

23. Erect hairs on the antennal scapes short, stout and blunt; color orange 

yellow hirticornis 

Erect hairs on the antennal scapes long, slender and pointed; color red- 
dish yellow diversipilosus 

24. Clypeus with a median carinula or with several carinulae; mesoepinotal 
suture seldom present on the thoracic dorsum and never impressed ... 29 
Clypeus without a median carinula, its center usually depressed to form 
a shallow, longitudinal trough; mesoepintoal suture regularly present on 
the thoracic dorsum and usually depressed slightly below the level of the 
rest of the thorax 25 

25. Erect body hairs numerous, long and usually pointed; interrugal punc- 
tures on the thorax heavy and dense, the surface feebly shining or opaque 

crassipilis 

Erect body hairs sparse, short and usually clavate; interrugal punctures 
on the thorax shallow and rather sparse, the surface where they occur 
moderately shining 26 

26. Antennal scapes with a few suberect hairs on their anterior surfaces. . . . 

canadensis subsp. kincaidi 
Antennal scapes with all hairs closely appressed 27 

27. The thoracic dorsum with distinct reticulo-rugose sculpture in addition 

to the dense punctures 28 

The thoracic dorsum densely punctate but with the rugae very feeble or 
absent canadensis subsp. yankee 

28. Color piceous brown, the thorax very rarely lighter than the head and 
gaster; mesonotal rugae less prominent than those of the pronotum and 

often largely replaced by punctures canadensis 

Head and gaster notably darker than the thorax, the latter usually red- 
dish yellow in color; mesonotum usually crossed by prominent rugae. . . . 

canadensis subsp. calderoni 

29. Epinotal spines longer than one-half the distance which separates their 

bases 30 

Epinotal spines short and dentiform, their length less than one-half the 
distance which separates their bases schaumi 

30. Dorsal surface of the head in large part strongly shining, the longitudinal 
rugae, if present, sparse and feeble, the interrugal sculpture consisting 

of small widely-scattered punctures longispinosus 

Dorsal surface of the head feebly shining or completely opaque, the sculp- 
ture variable but never of a character to give the surface a smooth and 
strongly shining appearance 31 

31. Head with the longitudinal rugae very delicate, not much coarser than 

the interrugal sculpture and often forming reticulations with it 32 

Head with coarse longitudinal rugae which are notably heavier than 

the interrugal sculpture and do not form reticulations with it 34 

32. The antennal scape in repose reaching the occipital margin .... duloticus 



CREIGHTON: ANTS OF NORTH AMERICA zo\) 

The antennal scape in repose failing to reach the occipital margin by an 
amount approximately equal to the length of the first funicular joint . . 33 

33. Epinotal spines set close together at the base; postpetiole, seen from 

above, subquadrate, very little broader than long curvispinosus 

Epinotal spines well-separated at the base; postpetiole, seen from above, 
notably broader than long ambiguus 

34. Interrugal punctures of the head very dense and coarse, the areas where 

they occur dull 35 

Interrugal punctures of the head fine and somewhat separated, the areas 
where they occur feebly shining 36 

35. Dorsum of the postpetiole lightly punctured, not completely opaque; 
dorsum of the mesonotum with the longitudinal rugae largely replaced 
by punctures; epinotal spines less than half as long as the distance which 

separates their tips bradleyi 

Dorsum of the postpetiole heavily punctured and completely opaque; 
dorsum of the mesonotum with the longitudinal rugae not replaced by 
punctures; epinotal spines more than half as long as the distance which 
separates their tips wheeleri 

36. Thoracic rugae well-developed rugatulus 

Thoracic rugae feeble, often replaced in part by punctures 

rugatulus subsp. brunnescens 



Subgenus GONIOTHORAX Emery 

1. LEPTOTHORAX (GONIOTHORAX) WILDA M. R. Smith 

L. (G.) wilda M. R. Smith, Proc. Ent. Soc. Wash., Vol. 45, p. 155 (1943) 9 9 ; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 572, pi. 11, fig. 

42 (1947) 9 . 
Type loc: Brownsville, Texas. Type: U.S.N.M. Paratypes: U.S.N.M., 

M.C.Z., A.M.N.H., Coll. Cal. Acad. Sci. 
Range: known from southern Texas only. 

This interesting species is the first member of the subgenus to be 
taken within our borders. It apparently nests in hollow twigs or the 
stems of vines. 



Subgenus DlCHOTHORAX Emery 

The status of the forms which compose this subgenus is very puz- 
zling. Since only five representatives have been described there 
would seem to be little chance for taxonomic confusion. Unfortu- 
nately this is not the case. These insects are highly variable in such 
traits as color, hair pattern and sculpture. Since such variations often 
appear within a nest series it is very difficult to select subspecific char- 



260 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

acters which are constant enough to give good separation. Added to 
this minor structural variation' is a distribution which argues against 
subspecific status for most of the forms. The ranges are so nearly 
coincidental that no geographical distinction is practical in several 
cases. Because of the above considerations I find it difficult to attach 
much taxonomic significance to the varieties flauus and spinosus, 
which seem best regarded as inconstant fluctuations which occur in 
the population of floridanus. Wesson has reached a similar conclu- 
sion for the species which he described in 1935 as manni. He now re- 
gards this insect as a synonym of pergandei. This leaves only per- 
gandei and floridanus. I have attempted to treat the latter form as a 
subspecies of pergandei, for the two are so similar structurally that it 
is unlikely that they represent separate species. But this treatment 
runs afoul of the fact that the two forms have ranges which overlap 
broadly in the region running westward from North Carolina to Okla- 
homa. It appears, however, that the range of pergandei extends fur- 
ther to the north than does that of floridanus and the latter insect has 
a southern and southwestern range which is separate from that of 
pergandei. It would not be surprising, however, if future investiga- 
tions show that it is not possible to separate pergandei and floridanw. 

2. LEPTOTHOEAX (DICHOTHOEAX) PERGANDEI Emery 

L. (D.) pergandei Emery, Zool. Jahrb. Syst., Vol. 8, p. 323, pi. 8, fig. 13 (1895) 
9 9 cT; Wheeler, Proc. Acad. Nat. Sci. Phila., p. 256, pi. 12, fig. 23 
(1903) 9 9 d". 

L. (D.) manni Wesson, Ent. News, Vol. 46, p. 208 (1935) 9 9 c?. 

L. (D.) manni Wesson, Ent. News, Vol. 50, p. 180 (1939) (synonymic note). 

Type loc: Washington, B.C. Types: A.M.N.H., M.C.Z. 

Range: rather sporadically distributed in the central Atlantic states south to 
Tennessee and North Carolina and west to Indiana. 



3. LEPTOTHORAX (DICHOTHORAX) PERGANDEI FLOHIDANUS Emery 

L. (D.) floridanus Emery, Zool. Jahrb. Syst., Vol. 8, p. 324 (1895) 9 ; Wheeler, 

Proc. Acad. Nat. Sci. Phila., p. 259 (1903) 9 . 
L. (D.) pergandei var. flavus M. R. Smith, Ann. Ent. Soc. Amer., Vol. 22, 

p. 549 (1929) 9 9 . 
L. (D.) pergandei subsp. floridanus var. spinosus M. R. Smith, Ibid., p. 551 

(1929) 9. 
L. (Dichothorax) sp. M. R. Smith, Amer. Mid. Naturalist, Vol. 27, No. 3, 

p. 574, pi. 12, fig. 44 (1947) 9 . 
Type loc: Florida. Types: A.M.N.H. 
Range: North Carolina to Florida and southwestward into Texas. 



CREIGHTON: ANTS OF NORTH AMERICA zol 

Subgenus LiEPTOTHORAX Mayr 

4. LEPTOTHORAX AMBIGUUS Emery 

The taxonomic status of ambiguus has been confused from the 
start, since Emery treated this insect as a subspecies of curvispinosus 
at the time of its original description in 1895. It was not until 1940 
that this situation was corrected. At that time the Wessons proposed 
specific status for ambiguus and redescribed the insect. The Wessons 
presented an excellent list of structural differences which distinguish 
ambiguus from curvispinosus. While these were quite adequate to es- 
tablish ambiguus as a separate species, it seems well to add certain 
other points which have a bearing on the specificity of ambiguus. 
On the basis of distribution the relationship of ambiguus to curvispino- 
sus is clearly that of a species, not a subspecies. Over a considerable 
part of the northeastern United States the two insects occur in the 
same stations with the nests often occurring within a few feet of each 
other. Despite this proximity there is no evidence that the two inter- 
grade. In addition, the habits of the two species show certain sig- 
nificant differences. L. curvispinosus nests by preference in preformed 
cavities, especially those which occur in' various plant tissues. The 
objects in which the nests are constructed either rest on the surface 
of the soil or are suspended above it. It is only rarely that a nest of 
curvispinosus is found with passages in the soil itself. The nests of 
ambiguus may also be constructed in plant cavities but those selected 
usually involve a much more intimate relation with soil. Thus, the 
Wessons report ambiguus nesting in the hollow stems at the base of 
grass tufts or free in the soil. The writer has always found ambiguus 
nesting in soil. Finally, there is indirect evidence to show that am- 
biguus is a more pugnacious ant than curvispinosus. I believe that I 
am correct in stating that as yet no record of the enslavement of 
ambiguus by Harpagoxenus has been reported. Since Harpagoxenus 
enslaves both longispinosus and curvispinosus, there would seem to be 
no reason why it should not also enslave ambiguus unless the last 
species is sufficiently enterprising to beat off the raids. 

Before presenting the citations for ambiguus, it is necessary to con- 
sider the status of two forms which are closely related to it. Dr. 
M. R. Smith now regards the insect which he described as the species 
foveata in 1934 as very closely related to ambiguus if not actually a 
synonym of that species. In 1940 the Wessons recognized a variety 
of ambiguus to which they gave the name pinetorum. The principal 
differences between foveata and ambiguus are to be found in the more 
robust petiolar nodes and a slightly stronger impression of the sides 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



of the thorax at the mesoepinotal suture in foveata. According to the 
Wessons, the epinotal spines of pinetorum are notably longer than 
those of ambiguus and the thoracic rugae of pinetorum are feebler. 
In both cases the differences are clearly discernible only when the 
variants can be compared with the typical form. For this reason I 
have made no attempt to include either foveata or pinetorum in the 
key. The problem of distinguishing between these variants and the 
typical ambiguus is by no means the only difficulty involved. We 
know practically nothing about the range of either insect. The two 
type specimens of foveata were taken at Plainfield, Illinois. The type 
series of pinetorum and several other nests of this form came from 
Jackson County, Ohio. Since it has been customary to regard the 
range of the typical ambiguus as extending from eastern Canada and 
New England to the Dakotas, there is little present help to be secured 
from the occurrence of both foveata and pinetorum at points approxi- 
mately in the middle of this range. But it is by no means certain that 
the population which has previously been regarded as the typical 
ambiguus is a uniform one. It may be recalled that Emery utilized 
material coming from South Dakota, Ohio and New York as type 
specimens of ambiguus. In order to reduce confusion which might 
arise from a mixed type series, I propose to restrict the type series 
of ambiguus to those specimens which were taken in Hill City, South 
Dakota. There are two reasons why this is advantageous. Specimens 
from this same series, which are authentic and presumably cotypes, 
are present in three American museums. In the second place, if there 
is any tendency for ambiguus to produce geographical races, it may be 
safely assumed that the Hill City specimens represent the western 
race, for this station appears to be close to the western limit of the 
range of the species. Before anything certain can be stated as to the 
exact relationship of foveata and pinetorum to the typical ambiguus 
it will be necessary to make a survey of the eastern population of 
ambiguus and determine to which of the three described forms this 
population belongs. Either foveata or pinetorum may prove to be an 
eastern race of the typical ambiguus. I confess that it seems very un- 
likely that both will prove to be valid subspecies and perhaps both 
may prove to be inconsequential variations which lack any distribu- 
tional significance. Until the matter can be definitely decided the two 
forms may be retained provisionally as subspecies. There follows 
the synonymy of Leptothorax ambiguus Emery: 

L. curvispinosus subsp. ambiguus Emery, Zool. Jahrb. Syst., Vol. 8, p. 320 
(1895) 9 ; Wheeler, Proc. Acad. Nat. Sci. Phila., p. 241, pi. 12, fig. 11 
(1903) V. 



CKEIGHTON: ANTS OF NORTH AMERICA 2bo 

L. ambiguus L. G. & R. G. Wesson, Amer. Mid. Naturalist, Vol. 24, No. 1, 
p. 97 (1940) 9 9 c?. 

Type loc: Hill City, South Dakota (by present restriction). Types: 
A.M.N.H., M.C.Z., U.S.N.M. 

Range: eastern Canada and New England west to the Dakotas. In the east 
the southern limit of the range seems to lie at the latitude of Pennsyl- 
vania and Ohio. 



5. LEPTOTHORAX AMBIGUUS FOVEATUS M. R. Smith 

L.foveata M. R. Smith, Psyche, Vol. 41, p. 211 (1934) 9 . 
Type loc: Plainfield, Illinois. Types: Coll. M. R. Smith. 
Range: known only from type material. 

For a discussion of the relationships of foveatus to ambiguus see the 
introduction to ambiguus. 



6. LEPTOTHORAX AMBIGUUS PINETORUM L. G. & R. G. Wesson 

L. ambiguus subsp. pinetorum L. G. & R. G. Wesson, Amer. Mid. Naturalist, 

Vol. 24, No. 1, p. 97 (1940) 9 9 o" . 

Type loc: Jackson County, Ohio. Types: Coll. Wessons. 
Range: known only from Jackson County, Ohio. 

For a discussion of the relationships of pinetorum to ambiguus see 
the introduction to ambiguus. 



7. LEPTOTHORAX ANDREI Emery 

L. andrei Emery, Zool. Jahrb. Syst., Vol. 8, pi. 8, fig. 15 (1895) 9 ; Wheeler, 

Proc. Acad. Nat. Sci. Phila., p. '256 (1903) 9 . 
Type loc: California. Types: none in this country. 
Range: known only from the coastal area of central California. 



8. LEPTOTHORAX BRADLEYI Wheeler 

L. bradleyi Wheeler, Psyche, Vol. 20, p. 113 (1913) 9 . 

Type loc: Billy's Island, Okefenokee Swamp, Georgia. Type: A.M.N.H. 

Range: known only from the single holotype. 



9. LEPTOTHORAX CURVISPINOSUS Mayr 

L. curvispinosus Mayr, Sitz-ber. Acad. Wiss. Wien, Vol. 53, p. 508, pi. 1, 
fig. 13 (1866) 9 ; Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 451 (1886) 



/o4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

9 9; Emery, Zool. Jahrb. Syst., Vol. 8, p. 317 (1895); Wheeler, Proc. 

Acad. Nat. Sci. Phila., p. 329, pi. 12, fig. 10 (1903) 9 9 . 
Stenamma gallarum Patton, Amer. Naturalist, Vol. 13, p. 126, note (1879) 9 9 . 
Type loc: 'North America'. Types: none in this country. 
Range: New England west to Iowa and Missouri and south to the Gulf Coast. 

In Mississippi and Alabama the insect is abundant only in the northern 

portions of the states. It is rare in the coastal area, although I have taken 

a few colonies as far south as Mobile. 



10. LEPTOTHORAX FURUNCULUS Wheeler 

L.furunculus Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 82 (1909) 9 . 
Type loc: Williams Canyon, Manitou, Colorado. Types: A.M.N.H., 

M.C.Z., Coll. W. S. Creighton. 
Range: known only from type material. 



11. LEPTOTHORAX LONGISPINOSUS Roger 

L. longispinosus Roger, Berl. Ent. Zeitschr., Vol. 7, p. 180 (1863) 9 ; Mayr, 

Verb. Zool-bot. Ges. Wien, Vol. 36, p. 451 (1886) 9 ; Emery, Zool. Jahrb. 

Syst., Vol. 8, p. 321 (1895) 9 9 ; Wheeler, Proc. Acad. Nat. Sci. Phila., 

p. 236, pi. 12, fig. 9 (1903) 9 9 d". 
L. (L.) longispinosus subsp. laeviceps Buren, Iowa State Coll. Jour. Sci., 

Vol. 18, No. 3, p. 287 (1944) 9 (nee Emery). 
L. (L.) longispinosus subsp. iowensis Buren, Proc. Ent. Soc. Wash., Vol. 47, 

p. 288 (1945). 

Type loc: 'America'. Types: none in this country. 
Range: eastern Canada and the northeastern United States west to Iowa. 

In the central Atlantic states the range follows the Appalachians and 

terminates in northern Georgia and northeastern Alabama. 

The writer can see little justification for the recognition of Buren's 
subsp. iowensis. This insect was originally described under the pre- 
occupied name, laeviceps. According to Mr. Buren, iowensis is a 
western race of longispinosus. It may be admitted that the presence 
of iowensis at the western end of the range of longispinosus favors 
such an interpretation. Unfortunately, this view is not supported by 
distributional data. Although Mr. Buren presented a number of 
features by which iowensis may be separated from the typical longi- 
spinosus, these differences do not, in my opinion, have a distributional 
significance. The single paratype of iowensis which Mr. Buren very 
kindly sent me differs in no way from the smaller and more lightly 
sculptured specimens which occur over the whole range of longispino- 
sus. For this reason it is impossible to regard iowensis as a western 



CREIGHTON: ANTS OF NORTH AMERICA ^oo 

race and, since it seems to be nothing more than one of the minor 
fluctuations which occur within the population of longispinosus, it 
is best regarded as a synonym of the typical form. 

12. LEPTOTHORAX MINUTISSIMUS M. R. Smith 

L. minutissimus M. R. Smith, Proc. Ent. Soc. Wash., Vol. 44, p. 59, pi. 6, 

figs. A, B (1942) 9 . 

Type loc: District of Columbia. Holotype and Paratypes: U.S.N.M. 
Range: known from type material only. 

The exact relationships of minutissimus are very puzzling. Dr. 
Smith is of the opinion that it may be a parasite on L. cunispinosus . 
The type series of minutissimus, consisting of several females, was 
associated with curvispinosus workers, although it is not certain that 
the two species came from the same nest. L. minutissimus is smaller 
than the female of cunispinosus and has a distinctly emarginate oc- 
cipital border. 

13. LEPTOTHORAX NITENS Emery 

L. nitens Emery, Zool. Jahrb. Syst., Vol. 8, p. 323, pi. 8, fig. 16 (1895) 9 ; 

Wheeler, Proc. Acad. Nat. Sci. Phila., p. 244, pi. 12, fig. 15 (1903) 9 . 
L. nitens var. mariposa Wheeler, Proc. Amer. Acad. Arts Sci. Boston, Vol. 52, 

p. 507 (1917) 9 . 
L. nitens subsp. occidentalis Wheeler, Proc. Acad. Nat. Sci. Phila., p. 245 

(1903) 9. 

Type loc: American Fork Canyon, Utah. Types: none in this country. 
Range: Utah and Colorado west to the Sierras of California. 

After examining the type material of the three variants which 
Wheeler allotted to nitens, I am of the opinion that only heathi is a 
valid subspecies. Fluctuations of color and variation in the coarseness 
of the thoracic punctures occur in the type series of both mariposa 
and occidentalis and I do not believe that these characteristics, which 
formed the basis for the recognition of the two variants, are suffi- 
ciently constant to be of taxonomic value. The subspecies heathi, on 
the other hand, is clearly distinguished by its short antennal scapes. 
It is, as Wheeler noted, unusually dark as well. 



14. LEPTOTHOHAX NITENS HEATHI Wheeler 

L. nitens var. heathi Wheeler, Proc. Acad. Nat. Sci. Phila., p. 245 (1903) 9 . 
Type loc: Pacific Grove, California. Types: A.M.N.H., M.C.Z., Coll. W. S. 
Creighton. 



zoo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Range: known only from type material. This seems to be a lowland sub- 
species. The typical nitens also occurs in California but is restricted to 
areas of considerable elevation in the Sierras. 



15. LEPTOTHOHAX NEVADENSIS Wheeler 

L. nevadensis Wheeler, Proc. Acad. Nat. Sci. Phila., p. 252, pi. 12, fig. 20 

(1903) 9 9 <?. 
Type loc: Kings Canyon, Ormsby County, Nevada. Types: A.M.N.H., 

M.C.Z. 
Range: eastern slopes of the Sierras from Lake Tahoe north to the Cascade 

Mountains of Washington. 

With the addition of more specimens it has been possible to show 
that Wheeler's species eldoradensis and melanderi are subspecies of 
nevadensis. Specimens coming from Sequoia National Park are ob- 
viously intergrades between rudis and eldoradensis and others from 
eastern Washington connect melanderi and the typical nevadensis. 
As yet no intergrades between nevadensis and rudis have been reported, 
but these must certainly occur, as the ranges of the two forms overlap 
in the region around Lake Tahoe. 



16. LEPTOTHOKAX NEVADENSIS ELDORADENSIS Wheeler 

L. eldoradensis Wheeler, Bull. Amer. Mus. Nat. Hist,, Vol. 34, p. 414 (1915) 9 . 

Type loc: Mt. Wilson, Pasadena, California. Types: M.C.Z. 

Range: Coastal Range and at lower elevations in the Sierras of California. 



17. LEPTOTHORAX NEVADENSIS MELANDERI Wheeler 

L. melanderi Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 81 (1909) 9 . 
Type loc: Moscow Mountains, Idaho. Types: A.M.N.H. 
Range: eastern Washington to western Montana. 



18. LEPTOTHORAX NEVADENSIS RUDIS Wheeler 

L. nevadensis subsp. ndis Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 52, p. 508 (1917) 9 9 . 
Type loc: Tenaya Canyon, Yosemite Valley, California. Types: M.C.Z., 

A.M.N.H., Coll. W. S. Creighton. 
Range: Sierras of California from Sequoia Park to Lake Tahoe. 



CREIGHTON: ANTS OF NORTH AMERICA zo 

19. 'LEPTOTHORAX OBTURATOR Wheeler 

L. obturator Wheeler, Proc. Acad. Nat. Sci. Phila., p. 242, pi. 12, fig. 19 (1903) 

9 9 c? . 

Type loc: Austin, Texas. Types: A.M.N.H., M.C.Z. 
Range: known from type material only. 



20. LEPTOTHORAX RUGATULUS Emery 

The taxonomic history of rugatulus is rather depressing. A lack of 
appreciation for certain characteristics of the typical form has re- 
sulted in the description of several subspecies and varieties most of 
which are invalid. I have examined a very large amount of material 
of rugatulus coming from ten western states. In this material were 
included types of all but one of the described forms. In addition, I 
have repeatedly studied this insect in the field. As a result, I am con- 
vinced that there are only two valid forms present, the typical ruga- 
tulus and the subspecies brunnescens. The color of these insects is 
highly responsive to environmental conditions. When the nests are 
situated in dry, sunny areas the workers will show little or no infusca- 
tion. Conversely, a shaded nest, or one in rather moist soil, is usually 
inhabited by dark workers. There is no evidence to show that these 
color phases have a distributional significance. It may be admitted 
that the population in the California Sierras averages darker than 
that in the Rockies but the full color range is present in both areas. 
The same consideration will apply to the color of the female. Wheeler 
was of the opinion that the variety mediorufus was distinguished by a 
large and very dark female. I have taken such large, dark females 
from nests in which the workers were almost without infuscation. 
The typical rugatulus also shows many slight variations in sculpture. 
These do not alter the basic pattern, which consists of rugae inter- 
spersed with punctures, but the abundance of the interrugal punc- 
tures, especially those on the head is rather variable, with the result 
that some specimens are more shining than others. Here again there 
is no evidence that such variation can be correlated with distribution. 
I have yet to see a nest series which is entirely constant in sculpture 
throughout. 

It may be appreciated, however, that one might be misled by such 
fluctuations if only a small amount of material were available for ex- 
amination. This has been the case with Wheeler's cockerelli, annectens 
and mediorufus, all of which must be regarded as synonyms of the 
typical rugatulus. Wheeler's brunnescens, on the other hand, shows 
constant and significant structural differences and a preference for 



258 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

nest sites at a high elevation which separates its range from that of 
rugatulus. The thoracic rugae of brunnescens are largely obliterated 
by the punctures and the cephalic rugae are feeble. While the cephalic 
sculpture of the typical rugatulus often approaches that of brun- 
nescens closely, these more lightly sculptured specimens of rugatulus 
always retain the thoracic rugae. The difference in appearance is 
very striking. 

The subspecies dakotensis, described by G. C. and E. W. Wheeler 
in 1944, is so certainly a synonym of brunnescens that I have little 
hesitation in synonymizing dakotensis, even though I have not seen 
type material of this form. The line by line agreement of G. C. and 
E. W. Wheeler's description of dakotensis with that of W. M. Wheeler's 
description of brunnescens is startling except for one difference. 
W. M. Wheeler described the postpetiole of brunnescens as being twice 
as wide as long, while G. C. and E. W. Wheeler described the post- 
petiole of dakotensis as one and one-quarter times as broad as long. 
A distinction of this magnitude requires more than passing comment. 
I believe, however, that the difference is more a matter of terminology 
than of structure. Unless I am very much mistaken, W. M. WTieeler 
excluded the anterior and posterior peduncles in making his estimate, 
hence the proportions which he presented apply to the node of the 
postpetiole only. Conversely, the proportions cited by G. C. and E. W. 
Wheeler clearly include the anterior and posterior peduncles. In an 
effort to check this matter I made micrometer measurements of the 
postpetiole of the types of brunnescens and also of specimens which 
Wheeler considered as the typical rugatulus. In both insects the pro- 
portions of the node of the postpetiole agreed very closely with the 
figures cited by W. M. Wlieeler. The width of the node is almost ex- 
actly twice its length and this proportion holds regardless of slight 
size differences in the worker. If, however, one included the an- 
terior and posterior peduncles, the proportions were more in line with 
those cited by G. C. and E. W. Wheeler. It may be recalled that 
G. C. and E. W. Wheeler consider the postpetiole of the typical ruga- 
tulus to be one and one-half times as broad as long. Since they state 
that the postpetiole of dakotensis is only one-sixth narrower than that 
of the typical rugatulus, it seems certain that the postpetiole of dako- 
tensis is not unusually narrow and that there is no great difference 
between the postpetiole of dakotensis and that of brunnescens. I feel 
certain that when the types of dakotensis can be compared with those 
of brunnescens, the two insects will prove to be identical. There fol- 
lows the synonymy of Leptothorax rugatulus Emery: 

L. rugatulus Emery, Zool. Jahrb. Syst., Vol. 8, p. 321 (1895) 9 ; Wheeler, 
Proc. Amer. Acad. Arts. Sci. Boston, Vol. 52, p. 509 (1917). 



CREIGHTON: ANTS or NORTH AMERICA zoy 

L. cwvispinosus subsp. rugatulus Wheeler, Proc. Aoad. Nat. Sci. Phila., p. 241, 
pi. 12, fig. 12 (1903) 9 . 

L. currispinosus subsp. annectens Wheeler, Ibid., p. 242, pi. 12, fig. 13 (1903) 9 . 

L. rugatulus var. cockerelli Wheeler, Ibid., p. 241 (1903) 9 9 . 

L. rugatulus var. mediorufus Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 
Vol. 52, p. 510 (1917) 9 9 . 

Type loc: Colorado (by present restriction). Types: A.M.N.H. 

Range: widely distributed throughout the Transition Zone in the Rocky 
Mountains, the Sierras and Cascades and the mountains of Arizona and 
Utah. An eastward extension of the range brings the insect into the 
Black Hills of South Dakota. The elevation at which rugatulus nests 
varies with the latitude but even in southern Arizona it does not nest 
above 7000 feet. 

21. LEPTOTHORAX RUGATULUS BRUNNESCENS Wheeler 

L. rugatulus subsp. brunnescens Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 
Vol. 52, p. 510 (1917) 9 . 

L. rugatulus subsp. dakotensis G. C. & E. W. Wheeler, North Dakota His- 
torical Quarterly, Vol. 11, No. 4, p. 247 (1944) 9 . 

Type loc: Creede, Colorado. Types: M.C.Z., A.M.N.H., Coll. W. S. Creigh- 
ton. 

Range: mountains of Colorado and Utah north to Montana and the Dakotas. 
In central Colorado the insect occurs at elevations of 8000 feet or more 
but descends to lower levels further north. 

It is possible to regard brunnescens as a subspecies of rugatulus 
since the ranges of the two are separated by elevation. However, 
there is less evidence of intergradation than might be expected and 
further investigation may show that brunnescens should be regarded 
as a separate species. The reasons for placing the subspecies dakoten- 
sis in the synonymy of brunnescens have been given in the introduction 
to rugatulus. 



22. LEPTOTHORAX SCHAUMI Roger 

In the present work fortinodis and its two varieties, melanoticus 
and gilvus, have been synonymized with schaumi. This treatment 
agrees in its principal point with the observations published by L. G. 
and R. G. Wesson in 1940. Neither the Wessons nor the writer be- 
lieve that fortinodis is specifically distinct from schaumi. The Wessons' 
contribution to the schaumi-fortinodis problem will be subsequently 
considered but first it seems advisable to review the steps by which 
the problem arose. 

Roger first described schaumi in 1863. No further mention was 
made of this insect until 1886. In that year Mayr described a second 



270 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

species, fortinodis, and presented a key which gave characteristics by 
which schaumi and fortinodis could be separated. The major dis- 
tinction which Mayr employed was that of color. The color of schaumi 
was given as reddish gold, that of fortinodis as brownish black. Even 
so, Mayr noted that he had seen one variety in which the head, thorax 
and petiole were reddish brown. As may be seen from the name which 
Mayr selected for his new species, he believed that it possessed a 
somewhat larger and thicker petiole than schaumi. But this struc- 
tural difference was subordinated to the much more apparent color 
difference, and when Emery published his Beitrdge in 1895 he threw 
over the petiolar difference arid relied on color entirely to secure sep- 
aration between schaumi and fortinodis. His judgment has since 
been proven absolutely sound. Wheeler's 1903 monograph of Lep- 
tothorax based the separation of the two insects on petiolar structure. 
Wheeler found himself forced to abandon color as a specific distinction 
because he had discovered a pale variant of fortinodis which he called 
gihus. The character of the type series of gilvus is worthy of note. 
It consisted of a deflated female and seven workers. The female and 
two of the workers were pure yellow in color. The remaining five 
workers were dark brown. They were, according to Wheeler, 'like 
the workers of the typical fortinodis'. If this were not enough to sug- 
gest that the two insects are cospecific, Wheeler supplied additional 
evidence in the closing paragraph of his description of gihus. Here 
Wheeler stated that the 'Austin specimens of fortinodis' as well as 
the types of melanoticus and gilvus all have smaller petioles than 
Mayr's type of fortinodis and 'suggest transitions to schaumi'. Wheel- 
er avoided the difficulty resulting from the mixed worker caste in the 
type nest of gilvus by a manreuver which appears to be unique in 
myrmecological taxonomy. Although he admitted that all the workers 
were offspring of the yellow female and postulated that the color 
differences which they showed were due to the fact that the yellow 
female had mated with a normal black male of fortinodis, Wheeler 
avoided the obvious issue of cospecificity by restricting the type of 
gilvus to the female only. He was thus able to continue the older prac- 
tice of treating schaumi and fortinodis as separate species. 

Since 1903 there has been a steady accumulation of evidence to 
show that 'mixed' colonies containing both black and yellow workers 
are by no means rare. The first careful analysis of such colonies was 
presented by the Wessons in 1940. They were able to give much valu- 
able data derived from a study of eight mixed colonies which they 
took in Ohio. In these colonies there appeared to be no correlation 
between the color of the worker and the character of the petiole. 
While the colors showed no tendency to intergrade, minor structural 



CREIGHTON: ANTS or NORTH AMERICA 271 

features varied and intergraded to a very large extent. The Wessons, 
therefore, concluded that if there was to be any separation between 
schaumi and fortinodis it would have to be on the basis of color alone. 
They pointed out that this color difference was not of sufficient sig- 
nificance to allow its use as the basis for separate specificity in the 
case of fortinodis. They proposed, therefore, to reduce fortinodis and 
melanoticus to a single color variety of schaumi. They left gihus 
strictly alone which, for reasons that have been given above, is about 
all that can be done with that extraordinary variety. The writer 
finds himself in complete agreement with the Wessons in this matter 
with the exception of using fortinodis as a varietal name. I have 
shown elsewhere that there is no justification for the use of formal 
names to describe the color phases of ants. It will cause no confusion 
if the light and dark phases of schaumi are referred to as such. I 
have, therefore, treated fortinodis, melanoticus and gilmis as synonyms 
of schaumi. There follows the synonymy of Lcptothorax schaumi 
Roger: 

L. schaumi Roger, Berl. Ent. Zeitschr., Vol. 7, p. 180 (1863) 9 ; Mayr, Verh. 
Zool-bot. Ges. Wien, Vol. 36, p. 451 (1886) 9 cf; Emery, Zool. Jahrb. 
Syst., Vol. 8, p. 320 (1895) 9 ; Wheeler, Proc. Acad. Nat. Sci. Phila., 
p. 232, pi. 12, fig. 7 (1903) 9 d 1 ; M. R. Smith, Amer. Mid. Naturalist, 
Vol. 37, No. 3, p. 574, pi. 12, fig. 43 (1947) 9 . 

L. fortinodis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 452 (1886) 9 9 ; 
Emery, Zool. Jahrb. Syst., Vol. 8, p. 318 (1895); Wheeler, Proc. Acad. 
Nat, Sci. Phila., p. 233, pi. 12, fig. 8 (1903) 9 9 . 

L. fortinodis var. gilvus Wheeler, Ibid., p. 235 (1903) 9 . 

L. fortinodis var. melanoticus Wheeler, Ibid., p. 235 (1903) 99.. 

Typeloc: Pennsylvania. Types: none in this country. 

Range: New England west to Iowa and southwest to Texas. The insect ap- 
pears to be fairly abundant in the eastern United States and as far south 
as South Carolina, but is rare in the eastern Gulf States and apparently 
absent in Florida. 

23. LEPTOTHORAX SCHMITTI Wheeler 

L. schmitti Wheeler, Proc. Acad. Nat. Sci. Phila., p. 242, pi. 12, fig. 14 (1903) 9 . 
Typeloc: Canyon City, Colorado. Types: A.M.N.H., M.C.Z. 
Range: known only from type material. 



24. LEPTOTHORAX SILVESTRII (Santschi) 

Tetramorium silvestrii Santschi, Bull. Soc. Ent. Ital., Vol. 41, p. 6 (1909) 9 . 
L. silvestrii Emery, in Wystman, Genera Insectorum, Fasc. 174, p. 258 (1922). 
Type loc: Tucson, Arizona. Types: none in this country. 
Range: known only from type material. 



^<2 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The fact that silvestrii was described by Santschi as a Tetramorium 
and later shifted by Emery to Leptothorax has made the generic 
affinities of this species questionable. Dr. M. R. Smith, with whom 
I have discussed this problem, is of the opinion that silvestrii should 
be treated as a doubtful species whose generic character cannot at 
present be determined. There is much to be said for this view but it 
leaves out of account the fact that Emery, whose caution in such 
matters was exemplary, had ample opportunity to ascertain the na- 
ture of silvestrii before he made the generic reallocation. In 1909 
Santschi had scarcely more than begun his myrmecological studies 
and was in close touch with both Forel and Emery. It is, therefore, 
entirely probable that Emery received authentic material of silvestrii 
from Santschi. Indeed, it is almost necessary to assume that this was 
the case, for there is little in Santschi's original description of silvestrii 
to indicate a relationship with the genus Leptothorax. Until the 
types of silvestrii can be re-examined, it seems preferable to trust 
Emery's judgement and to retain silvestrii in the genus Leptothorax. 

25. LEPTOTHORAX TERRIGENA Wheeler 

L. terrigena Wheeler, Proc. Acad. Nat. Sci. Phila., p. 254, pi. 12, fig. 21 (1903) 

9 9. 
Type loc: Austin, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creigh- 

ton. 
Range: known from type material only. 



26. LEPTOTHORAX TEXANUS Wheeler 

L. texanus Wheeler, Proc. Acad. Nat. Hist. Phila., p. 245, pi. 12, fig. 16 (1903) 

9 9<f. 

Type loc: Milano, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range : central Texas to southern Ohio. 

Gregg (1946) has recorded this species from northeastern Minne- 
sota. The record, which was based on a single worker, is rather more 
than suspect. It is scarcely credible that texanus, whose range west 
of the Mississippi lies mainly below the northern border of Oklahoma, 
should occur in Minnesota. As to what species Dr. Gregg had is 
questionable but it seems clear that it was not texanus. 



27. LEPTOTHORAX TEXANUS DAVISI Wheeler 

L. texanus subsp. davisi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 385 
(1905) 99. 



CREIGHTON: ANTS OF NOKTH AMERICA zt6 

Type loo: Lakehurst, New Jersey. Types: A.M.N.H., M.C.Z., Coll. W. S. 

Creighton. 
Range: pine barrens of New Jersey. The insect has also been taken on Long 

Island. 

There are so many striking structural differences which separate 
davisi from texanus that davisi could easily be regarded as a separate 
species. The question cannot be settled until we know more about 
the range of davisi. At present davisi is not known to occur south or 
west of New Jersey. There is, therefore, a considerable gap between 
its range and that of texanus. Additional field work may close this 
gap and we will then be in a position to evaluate the relationship of 
davisi to texanus. 



28. LEPTOTHORAX TRICARINATUS Emery 

L. tricarinatus Emery, Zool. Jahrb. Syst., Vol. 8, p. 321, pi. 8, fig. 14 (1895) V ; 
Wheeler, Proc. Acad. Nat. Sci., Phila., p. 247, pi. 12, fig. 17 (1903) 9 . 
Type loc: Hill City, South Dakota. Types: none in this country. 
Range: western South Dakota to central Iowa. 



29. LEPTOTHORAX TRICARINATUS NEOMEXICANUS Wheeler 

L. neomexicanus Wheeler, Proc. Acad. Nat. Sci. Phila., p. 248, pi. 12, fig. 18 

(1903) 9. 

Type loc: Manzanares, New Mexico. Types: A.M.N.H., M.C.Z. 
Range : northern New Mexico and Arizona. 

Wheeler regarded neomexicanus as a separate species but I believe 
that it is at most a southern race of tricarinatus. To judge from 
Emery's description of tricarinatus, the two forms are very similar. 
When the types of neomexicanus can be compared with those of tri- 
carinatus the two may prove to be identical. 



30. LEPTOTHORAX WHEELERI M. R. Smith 

eleri M. R. Smith, Ann. Ent. Soc. Amer., Vol. 22, p. 547, fig. 1 (1929) 
? 

" " College, Mississippi. Types: Coll. M. R. Smith, Coll. 
iss., M.C.Z., A.M.N.H., Coll. W. S. Creighton. 
jpi and Alabama north to Ohio. 



_.4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Subgenus MYCHOTHORAX Ruzsky 

31. LEPTOTHOKAX (MYCHOTHORAX) CANADENSIS Provancher 

In the present work I have returned to the position advocated by 
Carlo Emery in 1895 and reestablished canadensis as a separate spe- 
cies. I am fully aware that this view will meet with opposition be- 
cause of the long association of canadensis and its variants with 
.acervorum or muscorum. Yet I cannot see how any other course will 
give relief from the incongruities which have resulted from forcing 
the variants of canadensis into a scheme designed to care for Euro- 
pean species. 

It may be recalled that in the same year when Provancher de- 
scribed canadensis (1887), E. Andre, whose acquaintance with North 
American ants was slight, reduced Provancher's species to a variety 
of the European acervorum. That the two insects are similar may be 
admitted but that there was justification for Andre's action may be 
strongly denied. This was apparent to Emery who, in 1895, threw 
over Andre's arrangement and reestablished canadensis as a valid 
species. Had Emery's stand been followed, much subsequent diffi- 
culty might have been avoided. Instead, Wheeler elected to follow 
Andrei As a result the North American variants belonging to cana- 
densis were allocated either to acervorum or to muscorum, a practice 
for which there is no justification and one which has seriously damaged 
the taxonomy of the group. 

In order to make this clear it is necessary to consider briefly the 
characters which separate the European acervorum from muscorum. 
The thorax of acervorum is proportionally longer and lower than that 
of muscorum. The anterior face of the node of the petiole meets the 
summit in a distinct angle in acervorum, while in muscorum the sum- 
mit of the petiolar node is evenly rounded and lacks a distinct angle 
at the junction with the anterior face. The postpetiole of acervorum 
is proportionally larger than that of muscorum. As may be seen, 
none of the above characters are easily employed in a key, hence for 
practical purposes the two species are separated on the basis of tibial 
pilosity. The tibiae of muscorum have the hairs fully appressed, those 
of acervorum have the hairs erect or semierect but never fully appressed. 

On the basis of this last distinction, all the North American vari 
which have been assigned to acervorum would have to be transf' 
to muscorum. In every one of them the tibial hairs are fully a- 
a fact of which Wheeler was aware when he ass 1 
vorum. It is clear, therefore, that Wheeler utilizer' 
structure in making his allocations. But here the ; 



CREIGHTON: ANTS OF NORTH AMERICA zro 

better. There is not a single North American form assigned to acer- 
vorum in which the proportions of the postpetiole are comparable to 
those of the European form. They all have a comparatively small 
postpetiole which is certainly more like that of muscorum than that 
of acenorum. Why, then, may not these forms be regarded as repre- 
sentatives of muscorum? The difficulty lies in the fact that in every 
case the structure of the thorax and that of the petiolar node allies 
these forms to acenorum rather than to muscorum. 

It requires no particular acumen to appreciate that the present ar- 
rangement of the North American variants in the acervorum-muscorum 
complex is completely indefensible. There is no logical basis by which 
it can be justified and it is highly damaging not only to our own 
species but to acenorum and muscorum as well. With the North Am- 
erican variants of canadensis treated as representatives of acenorum 
and muscorum, the sharp distinction which marks the two European 
species is destroyed. There is no doubt whatever that acenorum and 
muscorum are separate species, for they not only show significant 
and constant structural differences but they maintain these over 
ranges which are extensive and largely coincidental. There can be 
no excuse for damaging this clear-cut situation by attempting to ex- 
pand the specific limits of acenorum and muscorum to include North 
American representatives which cannot properly be assigned to either 
species. By recognizing canadensis as a separate species, we will not 
only improve the taxonomic position of canadensis but also that of 
acenorum and muscorum as well. I believe that the complex of variants 
belonging to canadensis should be treated as follows : 

L. (Mychothorax) canadensis Provancher 

= var. convivialis Wheeler 

subsp. calderoni Forel 

= var. septentrionalis Wheeler 

subsp. kincaidi Pergande 

subsp. yankee Emery 

= var. sordidus Wheeler 
= var. obscurus Viereck 

The insect described by Wheeler as acenorum subsp. crassipitis 
must be regarded as a separate species. The arrangement proposed 
above is supported by zoogeographical data. Only two of the forms, 
the typical canadensis and the subspecies yankee, occur in the same 
geographical area and these two have ranges which are separated by 
different elevations. The ranges of all four subspecies merge in 
southern British Columbia and southwestern Alberta. In this region 



z/o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

numerous intergrades are produced. There follows the synonymy of 
Leptothorax (Mychothorax) canadensis Provancher : 

L. canadensis Provancher, Addit. Faune Canad. Hym., p. 245 (1887) 9 9 d"; 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 318 (1895) 9 . 

L. acervorum var. canadensis E. Andre, Rev. Ent. Caen, Vol. 6, p. 259 (1887) 9 . 
L. acervorum subsp. canadensis Wheeler, Proc. Acad. Nat. Sci. Phila., p. 225, 

pi. 12, fig. 4 (1903) 9 9 . 
L. (M.) acervorum subsp. canadensis M. R. Smith, Amer. Mid. Naturalist, Vol. 

37, No. 3, p. 574, pi. 12, fig. 45 (1947) 9 . 
L. acervorum var. convivialis Wheeler, Proc. Acad. Nat. Sci. Phila., p. 228 

(1903) 9. 

Typeloc: Cap Rouge, Ottawa, Ontario. Types: La valle Univ. Coll. Quebec? 
Range: coast to coast in Canada and the northern United States with a 

southern extension in the Rocky Mountain Region to Colorado. 

It is probable that canadensis occurs on many of the higher peaks 
in the southern Appalachians but its distribution south of Pennsyl- 
vania must be very discontinuous. Even in southern New York 
canadensis is rather strictly limited to mountainous areas. In the 
west the elevation at which canadensis occurs is notably affected by 
the latitude. In central Colorado the insect usually nests at eleva- 
tions of 8000 feet or more. In northern Montana the range descends 
to 4000 feet or less. In Canada the conditions apparently permit an 
uninterrupted swing to the east, although records from Saskatchewan, 
Manitoba and western Ontario are scarce. 

I have synonymized the variety convivialis with canadensis because 
it is impossible to attach any geographical significance to the slight 
differences of size and color on which this variety was established. 
Such variations occur throughout the entire range of the typical 
canadensis. 



32. LEPTOTHORAX (MYCHOTHORAX) CANADENSIS CALDERONI Forel 

L. (M.) acervorum subsp. canadensis var. calderoni Forel, Deutsche Ent. 

Zeitschr., p. 617 (1914) 9 9 . 
L. (M.) muscorum var. septentrionalis Wheeler, Proc. Amer. Acad. Arts Sci. 

Boston, Vol. 52, p. 511 (1917) 9 9 cf. 

Type loc: Lake Tahoe, California. Types: none in this country. 
Range: northern California into British Columbia and Alberta. 

The form described by Wheeler as muscorum var. septentrionalis 
is, in my opinion, an intergrade between calderoni and kincaidi. 



CEEIGHTON: ANTS OF NORTH AMERICA / 

33. LEPTOTHORAX (MYCHOTHOEAX) CANADENSIS KINCAIDI Pergande 

L. yankee var. kincaidi Pergande, Proc. Wash. Acad. Sci., Vol. 2, p. 520 

(1900) 9 9. 
L. acervorum subsp. canadensis var. kincaidi Wheeler, Proc. Acad. Nat. Sci. 

Phila., p. 227, pi. 12, fig. 5 (1903) 9 . 

Type loc: Metlakahtla, Alaska. Types: U.S.N.M., A.M.N.H., M.C.Z. 
Range: Alaska south through British Columbia and western Alberta to the 

mountains of Washington. 



34. LEPTOTHORAX (MYCHOTHORAX) CANADENSIS YANKEE Emery 

L. canadensis var. yankee Emery, Zool. Jahrb. Syst., Vol. 8, p. 319 (1895) 9 . 
L. acervorum subsp. canadensis var. yankee Wheeler, Proc. Acad. Nat. Sci. 

Phila., p. 227, pi. 12, fig. 5 (1903) 9 . 

L. muscorum var. Emery, Zool. Jahrb. Syst., Vol. 8, p. 318 (1895) 9 . 
L. muscorum var. sordidus Wheeler, Proc. Acad. Nat. Sci. Phila., p. 224, pi. 12, 

fig. 2 (1903) 9 . 
L. acervorum subsp. obscurus Viereck, Trans. Amer. Ent. Soc., Vol. 29, p. 72 

(1903) 9. 
Type loc: Hill City, South Dakota (by present restriction). Types: 

A.M.N.H., M.C.Z. 
Range: the Rocky Mountain region from New Mexico to British Columbia 

and east to the Black Hills of South Dakota. 

Although the range of yankee corresponds closely with the western 
portion of the range of the typical canadensis, the two insects are 
separated by an elevational difference which keeps them apart, except 
in southern British Columbia. As has already been noted, the typical 
canadensis occurs at elevations of 8000 feet or more in central Colorado. 
In this latitude the subspecies yankee usually occurs at elevations be- 
tween 5500 and 7000 feet. The elevational drop which occurs as the 
range of the typical canadensis runs northward is much less marked 
in the case of the subspecies yankee. Hence, the ranges of the two 
subspecies approach and meet in southern British Columbia. 

There would seem to be no doubt that Wheeler's variety sordidus 
is a synonym of yankee. When WTieeler described sordidus he had no 
types of yankee for comparison. Type material of yankee is now 
available for examination. I have been able to find no significant 
difference between the types of yankee and those of sordidus. It also 
seems clear that obscurus is a synonym of yankee and not, as Wheeler 
supposed, the same as convivialis. In this connection it seems worth 
noting that Wheeler was in error when he stated (1917) that the pub- 
lication of his 1903 monograph of Leptothorax antedated Viereck's 
description of obscurus. Actually, the paper carrying the description 



278 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

of obscurus appeared three months before Wheeler's monograph. 
This particular question of priority is actually a matter of no sig- 
nificance, since both forms involved are synonyms of much older vari- 



35. LEPTOTHORAX (MYCHOTHORAX) CRASSIPILIS Wheeler 

L. (M.) acervorum subsp. crassipilis Wheeler, Proc. Amer. Acad. Arts Sci. 
Boston, Vol. 52, p. 513 (1917) 9 9 cf . 

Type loc: Manitou, Colorado. Types: M.C.Z., A.M.N.H., Coll. W. S. 
Creighton. 

Range: an extensive although discontinuous range in Colorado, Wyoming, 
Utah, Nevada and Arizona. The insect usually nests in foothills at ele- 
vations not exceeding 7000 feet. 

The worker of crassipilis is very similar to that of canadensis, from 
which it differs mainly in sculpture and pilosity (see key). Neverthe- 
less, I believe that crassipilis is a distinct species. The epinotum and 
the petiolar node of the male of crassipilis are smooth and shining. 
In the male of canadensis and its variants these parts are sculptured 
and opaque. 

36. LEPTOTHORAX (MYCHOTHORAX) DIVERSIPILOSUS M. R. Smith 

L. (M.) diversipilosus M. R. Smith, Proc. Ent. Soc. Wash., Vol. 41, No. 5, 

p. 179 (1939) 9 . 

Type loc: Ft. Lewis, Washington. Types: U.S.N.M. 
Range: known only from type material. 

37. LEPTOTHORAX (MYCHOTHORAX) DULOTICUS L. G. W r esson 

L. (M.) duloticus Wesson, Ent. News, Vol. 48, p. 125, fig. 1, a, b (1937) 9 9 ; 
Wesson, Bull. Brooklyn Ent. Soc., Vol. 35, p. 83, fig. 1, a, b (1940) cT. 
Type loc: Jackson, Ohio. Types: Coll. L. G. Wesson, Coll. W. S. Creighton. 
Range: known only from Illinois and Ohio. 
Slaves: L. longispinosus, L. curvispinosus. 



38. LEPTOTHORAX (MYCHOTHORAX) HIRTICORNIS Emery 

L. hirlicornis Emery, Zool. Jahrb. Syst., Vol. 8, p. 319 (1895) 9 ; Wheeler, 
Proc. Acad. Nat. Sci. Phila., p. 224 (1903) 9 ; M. R. Smith, Proc. Ent. 
Soc. Wash., Vol. 41, No. 5, p. 177 (1939) 9 . 

L. (M.) hirticornis subsp. formidolosus Wheeler, Bull. Amer. Mus. Nat. Hist., 
Vol. 34, p. 415 (1915) 9 9. 



CREIGHTON: ANTS OF NORTH AMERICA z/y 

Type loc: Hill City, South Dakota. Types: none in this country. 
Range: western Dakotas to eastern Colorado. 

In a recent study of hirticornis Dr. M. R. Smith has cleared up 
several points which were difficult to explain. The type locality of 
hirticornis is Hill City, South Dakota and not Washington, D.C. as 
Emery supposed. This is entirely in consonance with field data on 
this species for all the records, except that for Emery's type specimen, 
come from areas in the Dakotas and Colorado. Dr. Smith has further 
shown that Wheeler's subspecies formidolosus is a synonym of hirti- 



39. LEPTOTHOKAX (MYCHOTHORAX) PROVANCHERI Emery 

L. tuberum Provancher, Natural. Canad., Vol. 5, p. 359 (1880) 9 ; Provancher, 

Faune Entomol. Canad. Hym., p. 602 (1883) 9 (nee Fabricius). 
L. provancheri Emery, Zool. Jahrb. Syst., Vol. 8, p. 320 (1895) 9 ; Wheeler, 

Proc. Acad. Nat. Sci. Phila., p. 229 (1903) 9 . 
L. emersoni Wheeler, Amer. Naturalist, Vol. 35, p. 433 (1901) 9 9 <? ; Wheeler, 

Proc. Acad. Nat. Sci. Phila., p. 230, pi. 12, fig. 6 (1903) 9 9 cf. 
L. (M.) emersoni subsp. hirtipilis Wheeler, Proc. Amer. Acad. Arts Sci. Boston, 

Vol. 52, p. 515 (1917) 9 . 

Type loc : Canada. Types : none in this country. 
Range: eastern Canada and New England west to Alberta. 

The original description of provancheri was made by Provancher. 
He made the mistake of confusing this insect with the European 
tuberum and presented what he thought was a redescription of tuberum 
in a paper published in 1880. Provancher later sent a specimen of his 
'tuberum' to Andr6, who gave it to Emery. Emery recognized Pro- 
vancher's homonym as a new species and described it under the name 
provancheri in 1895. Neither of these descriptions of provancheri is 
exhaustive but both stress one significant feature which clearly indi- 
cates the nature of provancheri. The postpetiole is described as smooth 
and shining, with short, longitudinal striae extending from its base 
onto the first gastric segment. These characteristics are very unusual 
in a member of the subgenus Mychothorax. They are, in point of fact, 
shown only by provancheri and Wheeler's emersoni. It seems clear 
that when WTieeler described emersoni, he had an imperfect knowledge 
of provancheri. The description which Wheeler gave for provancheri 
three years later is obviously a reshuffling of Emery's earlier descrip- 
tion. Wheeler was never able to assign specimens to provancheri be- 
cause he placed all such specimens with emersoni. In my opinion there 
is no doubt that Wheeler's emersoni is a synonym of provancheri. In 



ZsU BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

eastern Canada and New England the population of this species 
seems to be very uniform. In the west, where the range extends south- 
ward through the Rocky Mountains, it has produced the southern 
subspecies glacialis. Wheeler's hirtipilis is a form whose exact rela- 
tionships can never be ascertained, since it was described from a 
single worker. It may be said, however, that this single type specimen 
does not show the distinctive differences of sculpture which Wheeler 
cited as its definitive characteristics. Instead, it has a sculpture that 
is almost identical with that of the typical provancheri. I can see no 
justification for according subspecific status to hirtipilis, particularly 
in view of the fact that it was based on a single specimen. This speci- 
men is, nonetheless, of considerable importance, since it was taken in 
western Alberta. This seems to be the westernmost record for the 
typical provancheri to date. 

The relationship of provancheri to its 'host', Myrmica brevinodis, has 
been presented in the discussion at the beginning of the genus Lepto- 
thorax. 



40. LEPTOTHORAX (MYCHOTHORAX) PROVANCHERI GLACIALIS Wheeler 

L. emersoni subsp. glacialis Wheeler, Bull. Wisconsin Nat. His. Soc., Vol. 5, 

p. 71 (1907) 9 9 <f. 
Type loc: Florissant, Colorado. Types: A.M.N.H., M.C.Z., Coll. W. S. 

Creighton. 
Range: known only from type material. 



Genus OYMMYRMICA Wheeler 
(Plate 34, figures 1-2) 

In 1902 C. V. Chamberlin discovered, near Salt Lake City, three 
mixed nests consisting of Manica mutica and a small guest ant to which 
Wheeler subsequently gave the name Symmyrmica chamberlini. De- 
spite much subsequent examination of mutica colonies, no additional 
specimens of chamberlini have been taken. As a result, our knowledge 
of the habits of this insect is slight. Chamberlin observed that the 
inquiline constructed its own nest chambers so that they communi- 
cated with those of its host. The arrangement seems to be very 
similar to that found in the nests of Leptothorax provancheri, which is 
an inquiline of Myrmica brevinodis. It is possible that the relation- 
ships of chamberlini to mutica are similar to those of provancheri and 



CREIGHTON: ANTS OF NORTH AMERICA 281 

brevinodis but nothing certain can be stated until further observations 
can be made on this rare and interesting ant. 

The general structure of the worker of Symmyrmica is closely sim- 
ilar to that of certain species of Leptothorax but Symmyrmica may be 
easily separated because of its peculiar, ergatoid male. 



1. SYMMYRMICA CHAMBERLINI Wheeler 

S. chamberlini Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 5, pi. 1, 
figs. 1-7 (1904) 9 9 cf ; Wheeler, Ants, Columbia Univ. Press, p. 433, 
fig. 260 a-g (1910) 9 cf; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 
No. 3, p. 578 (1947) 9 cf. 

Type loc: Salt Lake City, Utah. Types: A.M.N.H., M.C.Z. 

Range: known only from type material. 

Host: Manica mutica. 



Genus HARPAGOXENUS Forel 
(Plate 35, figures 1-4) 

The genus Harpagoxenus is represented by only three species, the 
European sublaevis and the New World americanus and canadensis. 
All three of these insects enslave members of the genus Leptothorax. 
At present we know very little about the habits of H. canadensis. 
This is to be regretted, since there are indications that the habits of 
this insect may be of considerable phyletic interest. Like sublaevis 
it enslaves species belonging to the subgenus Mychothorax and like 
sublaevis it produces ergatoid females in considerable numbers. But 
unlike sublaevis it usually has normal females in the colonies as well. 
It would seem, therefore, that the position of canadensis is between 
that of sublaevis, where the ergatoid female has largely replaced the 
normal type, and that of americanus, in which the ergatoid female 
is rarely produced. The habits of sublaevis and americanus have been 
extensively recorded. The present account will deal mainly with those 
of the latter species. The first observations on the habits of ameri- 
canus were made by Wheeler in 1910. There followed other studies 
by Sturtevant (1925, 1927) and the writer (1927, 1929). The most 
recent contribution is a very comprehensive survey of the biology of 
americanus published by Wesson in 1939. As a result of these observa- 
tions, we now possess an unusually complete account of the activities 
of this insect. The essential features in the development of a colony 
of americanus are as follows: 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Immediately after the nuptial flight, which occurs in July, the 
fecundated americanus female seeks out a nest of L. curvispinosus or 
longispinosus. She attempts to enter this nest by force and, if suc- 
cessful, kills or drives away the Leptothorax workers and queen. From 
the brood, which she appropriates, presently emerge more Lepto- 
thorax workers who accept the americanus queen, feed her and tend 
the eggs which she lays. The americanus workers do not emerge until 
the following spring. In the mature colony the slave-raids do not 
begin until after the nuptial flight has taken place. The raids are pre- 
ceded by scouting forays in which individual americanus workers look 
for Leptothorax nests. When a nest is found the scout attempts to 
enter it and may succeed if the nest is a small one. If entry cannot 
be effected, the scout goes back to the home colony and returns with 
reinforcements. As a rule, the raiding band is a small one, rarely con- 
sisting of more than half a dozen workers, and is apt to break up en 
route to the scene of action. On reaching the Leptothorax nest the 
raiding party shows very little concerted action but their increased 
number usually permits them to force an entrance. The initial re- 
sistance of the Leptothorax is succeeded by panic. The Leptothorax 
then abandon their nest or make furtive attempts to carry out the 
brood until they are driven off or killed by the raiders. Having driven 
off the Leptothorax, the americanus workers appropriate their brood. 
The removal of this brood to the home nest is a lengthy process which 
may require several days. The brood is selectively treated, with a 
preference shown for worker pupae and large larvae. Small larvae, 
eggs and the pupae of sexual stages are usually rejected. Toward the 
end of the summer it frequently happens that one or more of the 
raiders remains permanently in the raided nest. This results in the 
formation of what Wesson has called a "secondary colony". What 
happens in this case is remarkable. The americanus worker becomes 
sexually functional and proceeds to lay eggs which may develop into 
workers, females and males. Wesson was able to show that the pro- 
portion of males produced under such circumstances is abnormally 
high and in many cases only males are produced. In several instances, 
however, these supposedly unfertilized, egg-laying workers produced 
female or worker eggs. This is a very remarkable situation and one 
which deserves additional study. 

There are two widely different interpretations concerning the sig- 
nificance of the habits of Harpagoxenus. Wheeler and the writer have 
considered the ants of this genus as degenerate slave-makers which 
are on the way to becoming workerless parasites. Wesson (1939) takes 
exception to this view. He regards Harpagoxenus as "occupying a 



CEEIGHTON: ANTS OF NORTH AMERICA zo 

position with respect to the Leptothorax which it enslaves quite analo- 
gous to that of Polyergus with respect to the Formicae enslaved by 
it." Wesson regards the position taken by Wheeler and myself as 
erroneous because our observations "happened to be limited for the 
most part to those that would give the impression of decadence in 
H. americanus". Wesson further objects strongly to the comparisons 
which Wheeler and I have drawn between the habits of Harpagoxenus 
and those of Polyergus. In this last particular I am inclined to agree 
that it is a mistake to contrast the behavior of two such dissimilar in- 
sects. In the broader view I remain unconvinced that Wesson has 
proven his contention. On the contrary, it appears that much of the 
excellent data which he has presented negates his position. Wesson 
draws a very convincing picture of the ferocity with which the ameri- 
canus worker attacks the members of the Leptothorax nest. My 1927 
paper, as well as that published in 1929, contained similar accounts. 
A highly organized slave raid should, however, consist of something 
more than the pugnacity of the individual. Wesson's observations 
show little evidence of well integrated raids on the part of americanus. 
He has called attention to the fact that raiders often penetrate small 
nests single-handed. His raiding parties were always small, frequently 
straggling, and the members of these parties acted without concerted 
effort in penetrating the raided nest. In my opinion the picture pre- 
sented by Wesson is still one in which the raiders act primarily on in- 
dividual initiative. It may be that 'degenerate' is the wrong term to 
apply to the slave raids of americanus but they assuredly cannot be 
regarded as paragons of efficiency in this respect. In addition, Wesson 
has presented data which seem remarkably pertinent in showing that 
the worker caste of americanus is undergoing reduction. In the thirty- 
two natural colonies which he had under observation the average num- 
ber of americanus workers was nine. In one exceptionally large colony 
the number ran to fifty but in no other colony were there more than 
twenty-five americanus workers present. I have observed this same 
phenomenon so often in the field that I have no doubt whatever that 
the average number of americanus workers in a colony is exceptionally 
low. This is precisely what one would expect to find in the case of a 
group tending toward the elimination of the worker caste but it 
scarcely fits the case if we are to regard Harpagoxenus as a dominant 
and aggressive slave maker. Finally, Wesson has observed the highly 
significant fact that americanus will mate in the nest. This condition 
is rarely encountered in ants but it is the rule in the nests of certain 
workerless parasites. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Key to the species of Harpagoxenus 

1. Median impression of the anterior margin of the clypeus broad and very 
shallow; front of the head finely punctate; rugae often replaced by punc- 
tato-granulose sculpture on the thoracic dorsum; node of the petiole, in 
profile, higher than its base is broad, the posterior peduncle short but dis- 
tinct americanus 

Median impression on the anterior margin of the clypeus narrow and rather 
deep; front of the head with delicate longitudinal rugae; thorax irregularly 
rugulose throughout; node of the petiole, in profile, as broad at the base as 
it is high, the posterior peduncle very indistinct canadensis 



1. HARPAGOXENUS AMERICANUS (Emery) 

Tomognathus americanus Emery, Zool. Jahrb. Syst., Vol. 8, p. 272 (1895) 9 - 
H. americanus Wheeler, Ants, Columbia Univ. Press, p. 494 (1910) 9 ; Creigh- 

ton, Psyche, Vol. 34, No. 1, p. 28, figs, la, 2a, b (1927) 9 d" ; M. R. Smith, 

Proc. Ent. Soc. Wash., Vol. 41, No. 5, p. 166, fig. 1 c (1939) 9 9 <?; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 574, pi. 12, 

fig. 46 (1947) 9 . 
Type loc: Washington, D.C. (worker); Tuxedo, New York (male); Jackson, 

Ohio (female). Types: worker and female, U.S.N.M.; male, Coll. W. S. 

Creighton. 
Range: Massachusetts and southeastern Ontario south to Virginia and west 

to Ohio. 
Slaves: Leptothorax longispinosus and curvispinosus. 



2. HARPAGOXENUS CANADENSIS M. R. Smith 

H. canadensis M. R. Smith, Proc. Ent. Soc. Wash., Vol. 41, No. 5, p. 169, 

figs. 1 a, b, 2a, b, c (1939) 9 ; Gregg, Canad. Ent., Vol. 77, p. 74, fig. la, 

b (1945) 9 . 
Type loc: Quebec, Canada (female); Duluth, Minnesota (worker). Types: 

female: U.S.N.M., M.C.Z., A.M.N.H., Can. Nat. Mus. Ottawa, Coll. 

W. S. Creighton; worker: U.S.N.M., Coll. R. E. Gregg. 
Range: Nova Scotia and Quebec west to Minnesota. 
Slave: L. (Mychothorax) canadensis. 

Through the generosity of Mr. Walley of the Ottawa Museum I 
was given a cotype from the type series of this interesting species. 
A study of this specimen has convinced me that it may be very diffi- 
cult to draw a hard and fast line between the 'simple ergatoid female' 
of canadensis and the worker. The median ocellus of the ergatoid is 
small and obscure and the thorax is extraordinarily like that of the 
worker. It would not be surprising if further investigation of this 



CREIGHTON: ANTS OF NOKTH AMERICA z8o 

species shows that all the workers can act as functional females. It 
is seldom that one encounters a genus which possesses so many enter- 
taining possibilities for investigation as Harpagoxenus. 



Genus TRIGLYPHOTHRIX Forel 

This genus, which is endemic to Africa and southern Asia, is repre- 
sented in the New World by a single "tramp" species striatidens. As 
nearly as can be determined, the original home of striatidens was 
southern India. Within the last half century this insect has been re- 
ported from tropical regions in all parts of the world. There have also 
been a number of records coming from stations well to the north of the 
tropics. Nearly all such records refer to colonies which have entered 
green-houses with introduced plants, but they are of interest because 
they indicate the ease with which this insect is dispersed by commerce. 
I have treated T. striatidens as a member of the North American ant 
fauna because there is now good evidence that this insect has been 
able to adapt itself to the conditions in the southeastern United States 
and is firmly established in that area. The first notice of the appear- 
ance of striatidens in America north of Mexico was the publication of a 
paper by Wheeler in 1916. The record was based upon specimens 
which had been taken by E. R. Barber at Audubon Park, Louisiana, 
in 1913. Since that time striatidens has been reported from Mississippi, 
Alabama, Florida and South Carolina. To judge from the few observa- 
tions which I have been able to make on this insect in southern Ala- 
bama, striatidens does not tend to dominate the area where it occurs. 
The tendency to overpopulation with the resulting depletion or ex- 
clusion of the native ant fauna is so often found in the case of intro- 
duced species of ants that the absence of this feature in the case of 
striatidens is worthy of note. In its native habitat striatidens is said 
to be a common and widely distributed insect. Its sporadic occurrence 
in the southeastern United States, where it is not at all abundant, 
may indicate that striatidens is barely able to hold its own against 
climatic conditions which are more rigorous than those of its original 
habitat. 

There is little likelihood that striatidens could be confused with any 
of our native ants. The trifid hairs, which are the generic character- 
istic of Triglyphothrix, are very distinct. In general appearance stria- 
tidens suggests a small, very hairy replica of Xiphomyrmex. It may 
be noted that the degree of elevation and the amount of curvature 
of the epinotal spines both vary in striatidens. Most of the American 
specimens which I have seen have perfectly straight epinotal spines 



28o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

which are much less elevated than those shown in Wheeler's 1916 
figure. They agree much more closely in this respect with the figure 
which Dr. Smith published in 1947. 

1. TRIGLYPHOTHRIX STRIATIDENS (Emery) 
(Introduced) 

Tetramorium obesum subsp. striatidens Emery, Ann. Mus. Stor. Nat. Geneva, 

Vol. 27, p. 501 (1889) 9 . 
T. striatidens Forel, Bombay Nat. Hist. Soc., Vol. 14, p. 704 (1902) 9 ; Bing- 

ham, Fauna Brit. India Hym., Vol. 2, p. 173 (1903) 9 ; Wheeler, Journ. 

Eeon. Ent., Vol. 9, No. 6, p. 568, fig. 39 (1916) 9 9 ; M. R. Smith, Amer. 

Mid. Naturalist, Vol. 37, No. 3, p. 579, pi. 13, fig. 47 (1947) 9 . 
Type loc: Bhamo, Burma. Types: none in this country. 
Range: (In the United States) southeastern United States north to the 

Carolinas. 



Genus TETRAMORIUM Mayr 
(Plate 36, figures 1-5) 

The five species belonging to this genus which have been taken in 
the United States present a number of interesting problems. All have 
been regarded as introduced ants. From a statistical standpoint the 
evidence for this view is strong. Tetramorium is unquestionably an 
Old World genus with the majority of the species showing paleotrdp- 
ical affinities. Moreover, three of the forms which occur in the New 
World, guineense, simillimum and pacificum, are tramp species which 
have been widely spread by commerce. A fourth, caespitum, occurs 
more widely in Europe and Asia than in North America. This leaves 
only lucayanum of the Bahamas and rugiventris of Arizona for which 
no Old World counterparts are known. Although the last species 
shows no evidence of. introduction, Dr. M. R. Smith has been at con- 
siderable pains to provide an explanation covering the possibility that 
it might be an introduced species. It would seem that we are never to 
get away from the view that there are no species of Tetramorium en- 
demic to the New World. In 1934 I presented evidence to show that 
caespitum should be regarded as a native North American species. 
I have seen nothing in the meantime which has altered my opinion. 
There is no sound reason why every species of Tetramorium which 
occurs in the New World must be regarded as an immigrant. I shall 
return to this matter in a subsequent paragraph but first it is necessary 
to consider the status of those species which are known to have been 
introduced. 



CEEIGHTON: ANTS OF NORTH AMERICA "* 

T. guineense, simillimum and pacificum fall into this category. The 
first two species are now so widely distributed that there is doubt as 
to exactly where they originated. It is generally believed that both 
are African. T. pacificum is a species endemic to Malaysia and the 
islands of the southwestern Pacific. The problem with these species 
is not their introduction but rather the question as to how they have 
reacted to introduction. Of the three, only guineense shows evidence 
of naturalization. This species now behaves as a native ant in many 
parts of the south. While it frequently enters buildings, it seems ca- 
pable of surviving winter conditions without protection, at least in 
the region bordering the Gulf of Mexico. Neither simillimum nor 
pacificum show a comparable behavior. It is possible that the first 
species has established itself in Florida and the last in California but 
the evidence is inconclusive in each case. It seems more probable that 
both species can survive only if given winter protection, hence they 
are 'established' under the artificial conditions which they find in 
dwellings and greenhouses. That either species has become a member 
of our ant fauna in the full sense of the term seems very questionable. 

We may now consider the case of caespitum and rugiventris, both of 
which are, in my opinion, native North American species. Since dif- 
ferent factors apply to these two species it is best to treat them 
separately. 

The range of caespitum in North America includes most of the 
eastern half of the United States. It has also been reported from Cali- 
fornia. In the eastern states the insect is nowhere very abundant ex- 
cept in certain areas along the Atlantic Coast. There is indisputable 
evidence that caespitum has been present in the region extending from 
the Atlantic Seaboard to the Mississippi Valley for more than half a 
century. In 1895 Emery reported caespitum from several Atlantic 
states as well as from Tennessee and Nebraska. W r e know, therefore, 
that fifty years ago the distribution of this insect in the United States 
was almost identical with what it is today. Since there is no recent 
evidence to indicate that caespitum is behaving as an introduced 
species, some remarkable assumptions have been advanced to cover 
this deficiency. 

About 1745 Peter Kalm was sent to this country from the Univer- 
sity of Abo to look for a mulberry tree that would resist cold. During 
his visit he observed many things, among them ants, and recorded 
the fact that in 1748 a small, brown ant was infesting houses in 
Philadelphia. In recent years Marlatt has associated this ant with 
caespitum and there is no reason why he could not be right. But it is 
one thing to show that caespitum may have been present in eastern 
America in colonial times and quite another to prove that the col- 



288 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

onists brought it here. Both Wheeler and Smith have fallen into this 
trap. In 1927 Wheeler observed that, if Marlatt was right in his 
association, then caespitum 'must have been introduced into the 
United States during colonial days'. In 1943 Smith stated that 
'there is every reason to believe that this species was brought in by 
the early colonists'. Both these statements are no more susceptible 
to proof than the claim that caespitum disembarked with the Pil- 
grims on Plymouth Rock. Both stem from the conviction that this 
species must be an introduced ant. The writer lacks that conviction. 

I believe that I am correct in stating that the only published data 
which can be cited in support of the view that caespitum is an imported 
species are those presented by Wheeler in 1927. In that year he re- 
ported the appearance of caespitum in metropolitan Boston. Since he 
was able to show that in earlier years the incidence of caespitum in 
New England had been very low, its comparatively sudden increase 
called for some explanation. Wheeler supplied this by assuming that 
the insect had migrated into Massachusetts from Connecticut. Wheel- 
er had found caespitum abundant in the latter state and southern 
New York as early as 1905. If Wheeler is correct in his belief that 
caespitum migrated into eastern Massachusetts during the period be- 
tween 1905 and 1927, this action is certainly not what one would ex- 
pect of a native species. On the other hand, it should be remembered 
that Wheeler made no claim that caespitum was absent from Massa- 
chusetts prior to the 'migration'. On the contrary, he mentioned speci- 
mens taken by Dimmock at Springfield (apparently about 1915). 
Hence the gain in incidence which Wheeler noted in 1927 is not cer- 
tainly attributable to migration and may have been due to conditions 
which favored the increase of a population already present. 

Since it seems so difficult to arrive at any positive data on the dis- 
tributional characteristics of caespitum in the New World, let us see 
if more satisfactory conclusions may not be drawn from its behavior 
elsewhere. T. caespitum differs from most of its congeners in that it 
cannot properly be considered a paleotropical species. The enormous 
range of caespitum begins in England and extends across Europe and 
northern Asia to Japan. There is a southern extension which sur- 
rounds the Mediterranean Basin, where the species has developed a 
multitude of minor variants. Two or three variants enter tropical 
Africa and one has reached the Kalahari Desert. But by far the 
greater part of the range of caespitum lies in a region where holarctic 
species occur. Despite its southern fringes in Africa, caespitum has 
a holarctic coverage which few species can match. Yet this fact is 
usually subordinated to its much less uniform occurrence in Africa. 
If we consider the holarctic affinities of caespitum, there is nothing at 



CREIGHTON: ANTS OF NORTH AMERICA zy 

all unusual in the fact that it should occur in Europe, Asia and North 
America. Many holarctic species occur on all three continents and 
such a circumpolar distribution is considered entirely natural. Why 
should it be necessary to make an exception in the case of caespitum? 

There can be little doubt as to why this has been done. Since guin- 
eense and simillimum are 'tramp species', caespitum has been marked 
with the same brand. This argument from analogy seems to have 
little basis in fact. It may be admitted that caespitum shows some 
slight tendency toward dissemination by commerce. The few_ records 
from southern Africa mentioned above are so far removed from the 
main range that it is difficult to account for them in any other way. 
But that this tendency reaches notable proportions may be strongly 
denied. There is no other conclusion to be drawn from the failure of 
caespitum to establish itself on the continents of South America and 
Australia. No comparable failures mark those ubiquitous tramps, 
guineense and simillimum. We have been attributing to caespitum 
distributional peculiarities which it does not possess. Hence its 'im- 
portation' to the United States is not the normal reaction of a 'tramp 
species' but an exceptional case. If caespitum has been imported to 
America, this represents the only instance in which the insect has been 
able to establish itself in a new continental area after importation. 

I have undertaken the lengthy discussion just presented because it 
seems clear that the idea of caespitum as an introduced species will 
not be easily displaced. It seems possible that a full review of the facts 
might succeed where data which I presented in 1934 have failed. Jn 
that year I described what I believed to be a new species of the rare, 
parasitic genus Anergates, whose host species is caespitum. The in- 
sect was taken in New Jersey. I had then, and have now, no doubt 
as to what this discovery meant as far as the status of caespitum is 
concerned. The discovery of Anergates in America rules out the possi- 
bility that caespitum might have been imported to this country. I 
confess that I did not greatly stress this point, for it seemed too ob- 
vious to require comment. But while the presence of Anergates in 
this country has been accepted, the implication of this fact on the 
status of caespitum has been avoided. Tetramorium caespitum is still 
treated as an imported ant and the theory that there can be no en- 
demic species of Tetramorium in the New World continues in full 
force. This has produced some rather surprising results, as may be 
seen from the following paragraph. 

In 1943 Dr. M. R. Smith described Tetramorium rugiventris. The 
type series of this interesting species was taken near Prescott, Ariz- 
ona. There was nothing whatever in the situation of the nest to indi- 
cate that the insect had been imported. There were, presumably, no 



zyU BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

dwellings nearby. The nest was secured in an upland grove of pon- 
derosa pines a mile from the main highway and ten miles south of 
Prescott. It would be hard to imagine a more unlikely station for an 
introduced species. Yet Dr. Smith felt it necessary to provide a way 
out for those who believe that there are no species of Tetramorium 
endemic to North America. He mentioned the possibility that rugi- 
ventris might have been introduced at the middle of the last century. 
At that time camels were brought to this country for use in desert 
transport in the southwestern states. If it is assumed that food and 
stores were brought from Africa with the camels, it may further be 
assumed that rugiventris might have come in with these stores. Dr. 
Smith's ingenious explanation is both entertaining and novel. Ento- 
mologists frequently strain at gnats but it is seldom that they are 
asked to swallow a camel. While I admire the tenacity with which Dr. 
Smith adheres to the 'tramp species' theory, I find myself unwilling 
to perform the mental gymnastics that such adherence now entails. 
Since everything points to rugiventris as a native species I propose to 
treat it as such until more convincing reasons are given as to why it 
should not be so considered. 

It may also be noted that the writer has followed Emery in treating 
Santschi's Tetramorium silvestrii as a member of the genus Lepto- 
thorax. Although silvestrii was described from specimens taken in 
Arizona and has a gastric sculpture which strongly suggests that of 
rugiventris, it seems preferable to concur with Emery's generic reallo- 
cation until the exact nature of silvestrii is better known. There would 
seem to be no limit to the problems connected with this difficult genus 
and it is to be hoped that additional efforts will be made to clear up 
some of the controversial points connected with our forms. The fol- 
lowing key is essentially that which Dr. M. R. Smith presented in his 
1943 study of Tetramorium. 



Key to the species of Tetramorium 

1. Antennal sulcus absent 2 

Antennal sulcus present 3 

2. Basal half of the first gastric segment longitudinally rugulose, subopaque; 
antennal scapes extending past the posterior border of the head; clypeus 
with a median impression; head and thorax rugulose reticulate, .rugiventris 
Basal half of the first gastric segment smooth and shining; antennal scapes 
not reaching the posterior border of the head; clypeus without a median 
impression; head and thorax longitudinally striated caespitum 

3. Hairs on head, thorax and petiolar nodes short, erect and enlarged apically ; 
head longitudinally rugulose, the spaces between the rugules finely granu- 
lose simillimum 



CREIGHTON: ANTS OF NORTH AMERICA 2V i 

Hairs and sculpture not as described above 4 

4. Node of the petiole in profile subrectangular, the top of the node not sloping 
forward and forming a sharp angle with the abruptly descending anterior 

face; color reddish yellow, the gaster brownish or blackish guineense 

Node of the petiole in profile with the upper face gradually sloping for- 
ward and meeting the anterior face in a very broadly rounded angle; color 
light brown or yellowish brown pacificum 

The total number of bibliographic citations for caespitum, guineense 
and simillimum is now very large. The lists presented below have 
been severely edited, particularly in the case of the older descriptions. 
Many of these are of little more than historical significance at present 
and it seems unnecessary to carry them when there are so many ade- 
quate descriptions of these species extant. For a more comprehensive 
listing the reader may consult the myrmicine section of Emery's 
Genera Insectorum (Fasc. 174, 1922). 



1. TETRAMORITJM CAESPITUM (Linne) 

Formica caespitum Linne, Syst. Nat. Ed. 10, Vol. 1, p. 581 (1758) 9 . 

T. caespitum Mayr, Verh. Zool-bot. Ver. Wien., Vol. 5, p. 246 (1855) ;Mayr, 
Europ. Formicid., p. 61 (1861); Forel, Fourmis Suisse, p. 72 (1874); 
E. Andre, Spec. Hym. Europe, Vol. 2, p. 285 (1882); Emery, Deutsche 
Ent. Zeitschr., p. 679, fig. 2 (1909); Donisthorpe, Brit. Ants, p. 170, 
pi. 9 (1915); Forel, Fauna Ins. Helvet. Hym. Form., p. 14 (1915); Emery, 
Bull. Soc. Ent. Ital., Vol. 47, p. 194, fig. 54 (1916); M. R. Smith, Amer. 
. Mid. Naturalist, Vol. 37, No. 3, p. 580, pi. 13, fig. 48 (1947) 9 . 

Myrmica brevinodis var. transversinodis Enzmann, Journ. N.Y. Ent. Soc., Vol. 
54, No. 1, p. 48, figs. 1, 2 (1946) 9 . 
All references are for all three castes unless otherwise noted. 

Type loc: 'in Europae tuberis'. Types: none in this country. 

Range: northeastern states south to Tennessee and west to Missouri and 
Nebraska. Also occurs in California. 



2. TETRAMORIUM GUINEENSE (Fabricius) 
(Introduced) 

Formica guineense Fabricius, Ent. Syst., Vol. 2, p. 357 (1793) 9 . 

T. guineense Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, .p. 972 (1870) 9 . 
E. Andre, Spec. Hym. Europe, Vol. 2, p. 288 (1892) 9 9 cf; Forel, Gran- 
didier Hist. Madagascar, Vol. 20, p. 154 (1891) 9 9 <f ; Bingham, Fauna 
Brit. India, Hym., Vol. 2, p. 184 (1903) 9 ; Emery, Deutsche Ent. Zeit- 
schr., p. 695 (1909) 9 9 G?; Arnold, Ann. So. Afr. Mus., Vol. 14, p. 306 
(1917) 9 ; M. R. Smith, Proc. Ent. Soc. Wash., Vol. 45, No. 1, p. 3, 
fig. 1 (1943) 9 . 



292 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: Guinea. Types: none in this country. 

Range: (in the United States) southern Florida to Texas. Scattered records 
from greenhouses in various parts of the country. 

It seems well to note that the episternal teeth or spines in the worker 
of guineense vary considerably in length. The spines may be short 
and toothlike (as shown in the figure of guineense which Dr. Smith 
presented in 1943) or they may be almost as long as the epinotal spines. 
Most of the specimens of guineense which the writer has examined 
have had fairly long episternal spines but Dr. Smith, who has exam- 
ined many thousands of specimens of guineense, writes me that in his 
opinion the spine length is not constant enough to be a reliable sepa- 
ratory character. 



3. TETRAMOEIUM PACIFICUM Mayr 
(Introduced) 

T. pacificum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 972 (1870) 9 9 . 
Type loc: Tongatabu, Friendly Islands. Types: none in this country. 
Range: (in the United States) California. 



4. TETRAMORIUM RUGIVENTRIS M. R. Smith 

T. rugiventris M. R. Smith, Proc. Ent. Soc. Wash., Vol. 45, No. 1, p. 4 (1943) 9 . 
Type loc: Prescott, Arizona. Holotype: U.S.N.M., Paratypes: A.M.N.H., 

M.C.Z. 
Range: known only from type material. 



5. TETRAMORIUM SIMILLIMUM (F. Smith) 
(Introduced) 

Myrmica simillimum F. Smith, List. Brit. Anim. Brit. Mus. part 6, Acul., 
p. 118 (1851) 9. 

T. simillimum Mayr, Europ. Formicid., p. 61 (1861) 9 ; Mayr, Verh. Zool- 
bot. Ges. Wien, Vol. 20, p. 972 (1870) 9 ; E. Andre, Spec. Hym. Europe, 
Vol. 2, p. 287-(1882) 9 9 cf; Bingham, Fauna Brit. India, Hym., Vol. 2, 
p. 185 (1903) 9 ; Emery, Deutsche Ent'. Zeitschr., p. 695 (1909) 9 9 cf; 
Arnold, Ann. S. Afr. Museum, Vol. 14, p. 326 (1917) 9 9 cf. 

Type loc: Dorsetshire, England. Types: none in this country. 

Range: (in the United States) southern Florida, with scattered records from 
greenhouses in various parts of the country. 



CREIGHTON: ANTS or NORTH AMERICA 4V6 

Genus XlPHOMYRMEX Forel 
(Plate 37, figures 1-4) 

The genus Xiphomyrmex is represented in the New World by a 
single species, spinosus, which has produced several subspecies in the 
southwestern United States and northern Mexico. X. spinosus and 
its subspecies are strictly limited to Sonoran areas. All the nests which 
I have taken have been situated on upland plains or in the foothills 
of mountains at elevations between five and six thousand feet. The 
colonies are small, seldom containing more than a hundred individuals 
and the insects are not particularly active. According to Wheeler, 
the workers forage singly but this is certainly not always the case. 
The nest is frequently surmounted by a small crater, especially when 
it is constructed in light soil, but in coarse soil the crater is often ab- 
sent. The insect appears to be carnivorous and is not believed to 
store seeds. 

The following key for the separation of the subspecies of spinosus 
is taken from the review of that species which was published by Dr. 
M. R. Smith in 1938. It does not include the typical spinosus, which 
does not occur north of the Mexican border. 

Key to the subspecies of Xiphomyrmex spinosus Pergande 

1. First gastric segment finely punctulate or shagreened, subopaque toward 

the base spinosus subsp. hispidus 

First gastric segment entirely smooth except for scattered piligerous punc- 
tures " 

. Metasternal angles acute, spiniform; thorax viewed from above with an in- 
distinct mesoepinotal constriction spinosus subsp. insons 

Metasternal angles blunt, not spine-like; thorax viewed from above with 
a distinct mesoepinotal constriction spinosus subsp. wheeleri 



1. XIPHOMYRMEX SPINOSUS HISPIDUS Wheeler 

X. spinosus subsp. hispidus Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
i. 415 (1915) 9 ; M. R. Smith, Jour. Wash. Acad. Sci., Vol. 28, No. 3, 
p. 129 (1938) 9 . 

Type loc: Tucson, Arizona. Types: M.C.Z., Coll. W. S. Creighton. 
Range : deserts of southern Arizona. 



2. XIPHOMYRMEX SPINOSUS INSONS Wheeler 

X. spinosus subsp. insons Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 
p. 416 (1915) 9 9 ; M. R. Smith, Jour. Wash. Acad. Sci., Vol. 28, No. 3, 



Zyi BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

p. 129 (1938) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No .3, 

p. 580, pi. 13, fig. 49 (1947) 9 . 
Typeloc: Austin, Texas. Types: M.C.Z. 
Range: western Texas. Most of the range of insons lies in the Trans-Pecos 

area. The type locality seems to be close to the eastern limit of the range. 



3. XlPHOMYRMEX SPINOSUS WHEELERI Forel 

Tetramorium (X.) wheeleri Forel, Ann. Soc. Ent. Belg., Vol. 45, p. .128 (1901) 9 . 
X. spinosus subsp. wheeleri Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 416 (1915) 9 ; M. R. Smith, Jour. Wash. Acad. Sci., Vol. 28, No. 3, 

p. 130 (1938) 9 . 

Typeloc: Pacheco, Zacatecas, Mexico. Types: A.M.N.H. 
Range : southern Arizona into Mexico. 

There has been some question concerning the status of material 
coming from the Huachuca Mountains which has been referred to 
wheeleri despite minor differences of structure. Both Wheeler (1915) 
and Smith (1938) noted the differences which distinguish these speci- 
mens but neither cared to give them a name. As I have a large series 
of specimens which were secured in the Huachucas in 1932, I believe 
that this difficulty may be resolved. A considerable proportion of the 
specimens appear to me to be indistinguishable from the Texas sub- 
species insons. A number of others, however, have a gastric sculpture 
which suggests a relationship to hispidus or spinosus. The area of 
shagreening is considerably reduced, but the base of the first gastric 
segment is distinctly sculptured. It would appear that these insects 
are intergrades between insons and hispidus. I entirely agree with 
Wheeler and Smith that it is inadvisable to name them. 



Genus WASMANNIA Forel 

This genus is represented in our ant fauna by a single introduced 
species, auropunctata, which has recently become established in 
southern Florida. It is not surprising that this insect should have 
made its appearance there, since it has been carried all over the tropics 
in both the Old and New World. Moreover, auropunctata appears to 
be an exceedingly adaptable species as far as the type of nest site is con- 
cerned. M. R. Smith (1936) has pointed out that it will tolerate all 
sorts of nesting conditions from heavy shade to areas of extreme dry- 
ness and intense illumination. On the other hand, auropunctata shows 
no such adaptability in the matter of mean yearly temperature. It 
requires tropical or subtropical conditions and apparently cannot 



CREIGHTON: ANTS OF NORTH AMERICA ^yo 

tolerate the climatic conditions which occur along the Gulf coast. 
The severity of the sting of this little ant is out of all proportion to its 
small size. Coupled with its practice of tending various aphids this 
makes auropunctata a rather undesirable addition to our ant fauna. 
It may, in course of time, become a serious pest in southern Florida 
but it is unlikely that it will be able to gain a foothold elsewhere. The 
northern limit of the range at present is in the vicinity of Ft. Lauder- 
dale. 

The appearance of the worker of auropunctata is quite distinctive 
and it is not apt to be confused with any of our native species. The 
antennae consist of eleven joints, with the last two forming a distinct 
club. The terminal joint of the club is more than a third as long as 
the remainder of the funiculus and is thickened in the middle so that 
it is much wider than the penultimate joint. The antennal scrobes 
are well-marked and extend almost to the occipital border. The 
thorax has very .pronounced humeral angles and a wavy, transverse 
welt across the pronotum just where the declivity to the neck begins. 
The epinotal spines are set close together at the base, strongly di- 
verging and slightly incurved when seen from above. The node of 
the petiole is rectangular in profile and higher than the postpetiole. 
The erect body hairs are long, coarse and rather sparse. 



1 . \YASMANNIA AUROPUNCTATA (Roger) 
(Introduced) 

Tetramorium auropunctatum Roger, Berl. Ent. Zeitschr., Vol. 7, p. 182 (1863) 

996"; Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 20, p. 375 (1884) 9 . 
W. auropunctata Forel, Trans. Ent. Soc. Lond., p. 383 (1893) 9 9 o"; Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 143, pi. 12, fig. 18 (1908) 9 ; 

M. R. Smith, Puerto Rico Univ. Jour. Agr., Vol. 20, p. 845 (1936) 9 ; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 582, pi. 13, fig. 50 

(1947) 9. 

Typeloc: Cuba. Types: none in this country. 
Range: (in the United States) southern Florida. 



Genus CRYPTOCERUS Fabricius 
(Plate 38, figures 1-6) 

In 1947 Dr. M. R. Smith published a highly detailed account of 
the three species of Cryptocerus which occur within our borders. 
Myrmecologists should find this paper useful, for it brings together 
much data on Cryptocerus which has formerly been widely scattered 



296 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

through the literature. This interesting Neotropical genus enters the 
United States at three widely separated points. C. varians occurs in 
southern Florida, C. texanus inhabits southwestern Texas and C. roh- 
weri is found in southern Arizona. 

Remarkably little is known concerning the habits of the members of 
this genus. It seems likely that most of the species are arboreal or at 
least prefer to nest in plant cavities. An interesting observation in 
this connection has been published by Dr. Neal Weber (1934). He 
observed that workers of C. varians, which he had under observation 
in an artificial nest, could run backwards as fast as they could run 
forward. He interpreted this as a response to a life spent in hollow 
twigs where, it may be presumed, a good deal of backing-up would be 
necessary. This species has another curious reaction which the writer 
has often observed. The body of this insect is flattened in a dorso- 
ventral plane with the dorsal surface in particular showing a remark- 
ably level contour. If disturbed they take full advantage of the pro- 
tection which this gives by flattening themselves as close to the sub- 
strate as possible. When they have assumed this crouching position 
it is almost impossible to pick them up unless tweezers are used. 
This reaction is quite unlike that of many arboreal ants which rely 
on their agility to escape molestation. Both Emery and Wheeler 
have assumed that the extraordinary saucer-like head of the major 
worker of Cryptocerus is used for blocking up the nest entrance. 
While there is no reason to doubt this assumption, there seems to be 
nothing but indirect evidence to support it at present. In 1905 
Wheeler published a brief account of several nests of C. varians which 
he had found in hollow twigs. The opening into each nest was ex- 
actly the size and shape of the head of the major worker. The majors 
could, therefore, fulfill the function of a living door, as do those of 
Colobopsis. As to whether they actually do so will have to be deter- 
mined by additional observations. Our three species may be sepa- 
rated as follows : 

Key to the species of Cryptocerus 

1. Upper surface of the head of the major forming an oval, concave, saucer- 
like structure which is closed in front except for a very narrow slit; epino- 
tum of the smallest workers much depressed, the declivious face extremely 
short and largely hidden by the first petiolar node (Subgenus Cyatho- 

myrmex) varians 

Upper surface of the head of the major similar in structure but with the 
anterior rim open above the mandibles; epinotum of the smallest workers 
not notably depressed, the declivious face clearly visible above the first 
petiolar node (Subgenus Cryptocerus) 2 



CREIGHTON : ANTS OF NORTH AMERICA Zyt 

2. Head and thorax of the major worker with the pit-like impressions de- 
void of hairs "except on the epinotum; gastric sculpture of the major in- 
cluding longitudinal rugulae at the base; thoracic sculpture of the minor 
in part longitudinally rugulose; gaster in all sizes of worker, entirely black 

rohweri 

Head and thorax of the major worker with a silvery hair arising from most 

of the pit-like impressions; gaster of the major sculptured but without 

basal rugulae; thoracic sculpture of the minor not longitudinally rugulose; 

gaster in all sizes of worker, with two yellowish or whitish basal spots . . . 

texanus 



Subgenus CRYPTOCERUS Fabricius 

1. CRYPTOCERUS ROHWERI Wheeler 

Cryptocerus (Cyathocephalus) rohweri Wheeler, Proc. N. E. Zool. Club., Vol. 6, 

p. 32, figs. 2'a, b (1916) V 01. 
C. (Cryptocerus) rohweri Emery, Genera Insectorum, Fasc. 174, p. 310 (1922); 

M. R. Smith, Proc. Ent. Soc. Wash., Vol. 49, No. 1, p. 34 (1947) 9 21 9 ; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 584, pi. 14, fig. 51 

(1947) 21. 

Type loo: Buehman Canyon, Santa Catalina Mts., Arizona. Types: M.C.Z. 
Range: southern Arizona. 

Wheeler originally assigned rohweri to the subgenus Cyathocephalus 
(now Cyathomyrmex), but there is no doubt that Emery was correct 
in reallocating the insect to the subgenus Cryptocerus. As Dr. Smith 
has pointed out, the type locality of rohweri is Buehman Canyon, not 
Buckman Canyon as Wheeler originally gave it. The type series was 
taken at an elevation of 3300 feet, and subsequent records indicate 
that the insect prefers to nest at low elevations in foothill canyons. 



2. CRYPTOCERUS TEXANUS Santschi 

Cryptocerus texanus Santschi, Bull. Soc. Ent. Fr., p. 208, fig. 2 (1915) 9 01. 
C. (Cryptocerus) texanus M. R. Smith, Proc. Ent. 'Soc. Wash, Vol. 49, No. 1, 



Type loc: Texas. Types: none in this country. 

Range: southwestern Texas, from San Antonio and Columbus south to 
Brownsville and into northern Mexico. 

This species has been plagued by several annoying errata resulting 
from carelessness on the part of Santschi and WTieeler. Since these 
have not had any serious effect on the status of texanus, I see no cause 



ZVQ BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

for reviewing them here. Those who are interested in such taxonomic 
curiosities will find a careful and discriminating treatment of the 
matter in Dr. Smith's paper cited above. It seems well to state, how- 
ever, that prior to 1915 Wheeler's references to texanus were given 
under the name angustus. 



Subgenus CYATHOMYRMEX Creighto: 

3. CRYPTOCERUS (CYATHOMYRMEX) VARIANS F. Smith 

Cryptocerus varians F. Smith, Trans. Ent. Soe. Lond., p. 606, pi. 11, fig. 6 
(1876) 9 ; Emery, Bull. Soc. Ent. Ital., Vol. 26, p. 211, pi. 4, fig. 33 
(1894) 9 ; Wheeler, Bull. Amer. Mus. Nat, Hist,, Vol. 21, p. 102, pi. 7, 
figs. 1-6 (1905) 9 21 9 cf ; Wheeler, Ants, Columbia Univ. Press, p. 90 
(1910) 9 01 9 cT. 

C. (Cyathocephalus) varians Wheeler, Bull. Mus. Comp. Zool. Harvard, Vol. 
90, p. 212, pi. 54 (1942) 9 21. 

C. (Cyathomyrmex) varians M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 
No. 3, p. 584, pi. 14, fig. 52 (1947) 9 . 

Type loc : Antilles (no particular island designated). Types : British Museum, 
if still extant. 

Range: (in the United States) southern Florida. 

This species is well named as far as color is concerned. The ma- 
jority of the workers in a colony usually have a piceous brown colora- 
tion on the head and thorax with the gaster and the appendages a red- 
dish brown. From this condition the color grades through castaneous 
brown to golden yellow. It has been generally assumed that these 
lighter colored individuals are callows but the writer is inclined to 
doubt this. Their integument is fully as hard as that of the dark 
colored workers and I have found them foraging outside the nest 
with the darker workers. 



Genus STRUMI GEN YS F. Smith 
(Plate 39, figures 1-5) 

The bizarre structure and highly specialized habits of the members 
of this genus make these insects especially interesting objects for study. 
It is regrettable that their small colonies are so difficult to find. We 
have very little information on the habits of many of our species. 
The outstanding contribution to the ecology of our North American 
forms of Strumigenys are the studies of L. G. and R. G. Wesson (1936, 



CREIGHTON: ANTS OF NORTH AMERICA zyy 

1939). These investigators made observations in the field and on cap- 
tive colonies in the case of several species. The habits of all the species 
studied were, in the main, remarkably constant. In each case the 
dietary staple of these ants was some species of. Collembola. When 
one has observed the great deliberation with which Strumigenys 
moves, it seems remarkable that they should have adapted them- 
selves to a diet consisting of insects so much more active than them- 
selves. The collembolans are captured more by stealth and patience 
than by the foraging methods common to most ants, although certain 
species of Strumigenys will try to track down their prey. As a rule, 
however, the ant waits for the collembolan to blunder into its open 
mandibles, even when this has been preceded by a reconnaissance 
which has brought the two insects close together. The mandibles of 
Strumigenys can be opened to an unusual degree. In some species 
they can be brought back until their outer borders are almost in con- 
tact with the sides of the head. As to whether this is true of the 
species in the subgenus Trichoscapa is not clear from the Wessons' 
observations, but the writer has repeatedly observed it in the case of 
S. louisianae subsp. laticephala (1937). The widely opened mandibles 
have the same function as the jaws of a trap and are 'sprung' by con- 
tact with trigger hairs or maxillary lobes which project beyond the 
clypeal border. The closure of the mandibles is extraordinarily rapid 
and the insect which springs the trap is almost certain to be impaled 
on the sharp mandibular teeth, since the trigger hairs and lobes are 
shorter than the mandibles. The victim is stung and rapidly immo- 
bilized once it has been grasped by the mandibles. The writer has 
been able to make observations on laticephala which indicate that the 
mandibular mechanism may also be employed in defense. A number 
of small ants which were introduced into an artificial nest of lati- 
cephala were attacked and killed. In this case the Strumigenys did 
not wait for their victim to come to them but closed in on the in- 
truder in a concerted attack. Although several Strumigenys would 
often be in close proximity during these attacks, they never struck 
each other with the mandibles. It is interesting to note that the dead 
ants were not used for food but were carried out and dumped on the 
refuse heap. There is no question that the dietary restriction of 
Strumigenys is high. The Wessons have been unable to get some of 
the species to eat anything but Collembola. The laticephala colony 
mentioned above fed on egg yolk or the dissected tissues of other in- 
sects, from which they sucked the juices. 

The nests of Strumigenys are constructed in a variety of places. 
They are frequently found in rotten, punky wood but have also been 
taken in pine duff, in thick humus, under bark and in the soil beneath 



BULLETIN: MUSEUM OF COMPAHATIVE ZOOLOGY 



stones and planks. Not infrequently these insects have been found 
in or near the nests of other genera of ants. Wesson believes that in 
such cases the Strumigenys are preying on the Collembola which often 
infest the nests of ants. He was able to show that in an artificial nest 
containing both Strumigenys pergandei and Aphaenogaster fulva, the 
larger insects made no attempt to molest the Strumigenys, although 
they were aware of their presence. As the Strumigenys maintained 
the individuality of their own nest chambers and resented the intru- 
sion of the Aphaenogaster workers, the relationship between the two 
insects seems comparable to that existing between Leptothorax provan- 
cheri and Myrmica brevinodis. In the above case the only benefit which 
the larger ant would derive would be the gain resulting from the re- 
moval of the Collembola by the Strumigenys. 

For many years the taxonomic status of the North American species 
of Strumigenys remained essentially in the form given it by Emery 
in 1895. At that time only seven representatives of the genus were 
known to occur in the United States. When Dr. M. R. Smith mono- 
graphed this genus in 1931, he doubled the number of recognized 
forms. In subsequent years there has been a steady advance in the 
development of the group. In the present paper twenty-five species 
and subspecies are recognized. While the taxonomy of Strumigenys 
is not unusually difficult, the genus shows several features which can 
produce confusion. One of the most curious characteristics, at least 
as far as the majority of our species are concerned, is the extraordinary 
similarity of thoracic structure. As a general rule species of ants will 
show differences both in cephalic and thoracic structure. This is not 
the case with Strumigenys. The thoracic structure in most of our 
species is so similar that it is safe to say that, if one removed the 
heads of the insects, separation to species would be largely a matter 
of guess. This peculiarity is reflected in the several keys which have 
been presented. All of them are based mainly on cephalic characters. 
These characters have to do with the shape of the head, its sculpture 
and pilosity. It not infrequently happens that the peculiar, squamose 
hairs which occur in many of the species are so closely set that they 
obscure the outline of the parts which they cover. This is particularly 
true of those hairs which border the clypeus. Since the shape of the 
clypeus is an important diagnostic character in many cases it is often 
necessary to wet the head of the specimen with some liquid which 
will cut down the diffusion of light caused by the hairs before one can 
be certain of the shape of the clypeus. The same technique will give 
good results in the case of the mandibular teeth which are usually ob- 
scured by covering hairs. The constancy of tooth pattern appears to 
be very high and the type of dentition is a good character for separa- 



CREIGHTON: ANTS OF NORTH AMERICA dUl 

tion. The shape of the head, although it has been more widely used in 
existing keys, is apparently less constant. Kennedy and Schramm 
(1933) have shown that in the case of dietrichi there may be consider- 
able variations in head shape within a nest series. The above con- 
sideration has led me to minimize head shape wherever possible in 
the following key. 



Key to the species of Strumigenys 

1. Mandibles long and slender, the apex of each mandible armed with two 
large teeth set one behind the other, the remainder of the inner border of 
the mandible unarmed except for a single, small, subapical tooth (Sub- 
genus Strumigenys) 2 

Mandibles much shorter, with the inner border armed with several teeth 
along its distal half and with a single, large triangular tooth at the base 
(Subgenus Trichoscapa) 3 

2. Average size 2.5 mm.; head broad posteriorly, with the occipital in- 
cision more than half as wide as the greatest width of the head 

louisianae subsp. laticephala 

Average size 2.25 mm.; head narrow posteriorly, with the occipital in- 
cision narrow and abrupt and not more than one-third as wide as the 
greatest width of the head louisianae 

3. Dorsal surface of the first gastric segment shagreened, subopaque; infra- 
spinal lamella absent margaritae 

Dorsal surface of the first gastric segment smooth and shining; infra- 
spinal lamella present 4 

4. Prothorax flattened and laterally margined; head largely destitute of 

hairs membranifera subsp. simillima 

Prothorax not flattened or, if flattened, not margined; head with nu- 
merous hairs 5 

5. Basal mandibular tooth fully exposed when the mandibles are closed; 

scapes strongly bent at the base 6 

Basal mandibular tooth partially or completely covered by the clypeus 
when the mandibles are closed; scapes not strongly bent at the base. . .7 

6. Anterior edge of the clypeus straight and forming sharp angles with the 

sides; scapes bent at right angles angulata 

Anterior edge of the clypeus convex and gradually passing to the sides; 
scapes bent at less than a right angle pergandei 

'. Clypeus in large part smooth and shining, without sculpture, or with the 

sculpture not heavy enough to dull the shining surface . . . : 8 

Clypeus heavily sculptured over most or all of its surface, opaque or 
subopaque in appearance 12 

8. Hairs on the clypeus long and few; marginal groove of the clypeus very 

distinct bimarginata 

Hairs on the clypeus abundant or, if few, the marginal groove is absent . 9 

9. Clypeus subquadrate, broader than long, the anterior border only mod- 



BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 



erately convex; hairs broadly squamose and so closely appressed that they 

partially obscure the shining surface of the clypeus rohweri 

Clypeus longer than broad, the sides distinctly converging towards the 
strongly convex anterior border; clypeal hairs not as above 10 

10. Clypeal hairs very abundant, fine, straight, not enlarged apically and 

with their tips pointed pilinasis subsp. laevinasis 

Clypeal hairs sparse or moderately numerous, enlarged apically or with 
the tips blunt 11 

11. Clypeus with not more than a dozen long hairs which do not form a mar- 
ginal fringe ornata 

Clypeus with moderately nume'rous, short, curved hairs which form a 
distinct marginal fringe brevisetosa 

12. Entire head and promesonotum covered with numerous, spoon-shaped, 

squamose hairs creightoni 

Squamose hairs, when present, less extensively distributed than above. 13 

13. Clypeal hairs long, their length one-third to one half the width of the 

clypeus 14 

Clypeal hairs short, their length seldom as much as one-fourth the width 
of the clypeus 16 

14. Clypeal hairs fine and abundant, more than fifty present 15 

Clypeal hairs coarse and sparse, not more than fifteen present . . . dietrichi 

15. Hairs on the margin of the clypeus strongly curved and slightly broadened 

and flattened toward the apex medialis 

Hairs on the margin of the clypeus weakly curved or straight, not at all 
flattened or broadened toward the apex pilinasis 

16. Thorax with four large and conspicuous hairs, one of which occurs at each 
humeral angle and one at each side of the thorax where the mesonotal 

declivity begins roslrata 

Thoracic pilosity not as above 17 

17. Clypeal hairs slightly, or not at all, enlarged and flattened apically, never 

strongly spatulate or spoon-shaped 18 

Clypeal hairs distinctly enlarged and flattened apically; notably spatulate 
or spoon-shaped 20 

18. Erect hairs on the clypeal margin all of about the same length, all strongly 
curved forward and together forming a conspicuous, even fringe .... talpa 
Erect hairs on the clypeal border uneven in length and not all curved 
forward, the fringe which they form ragged and inconspicuous 19 

19. The length of the erect hairs on the clypeus less than one-eighth of the 

width of the clypeus, the hairs bent but not S-shaped ohioensis 

The length of the erect hairs on the clypeus distinctly more than one- 
eighth the width of the clypeus, the hairs mostly S-shaped manni 

20. Length of the clypeus (from the middle of the anterior margin to the 
frontal area) as great as, or slightly greater than, its maximum width. . . 

clypeata 
Clypeus slightly but distinctly broader than long 21 

21. Mandibles at least one-fourth as long as the rest of the head, the basal 
tooth partly exposed abdita 



CREIGHTON: ANTS OF NORTH AMERICA 



Mandibles not more than one-sixth as long as the rest of the head, the 
basal tooth completely covered 22 

22. Middle of the clypeus depressed, its posterior portion rising suddenly to 

the level of the frontal lobes 23 

Middle of the clypeus not depressed, evenly sloping from its anterior 
edge to the level of the frontal lobes 24 

23. Each lateral border of the clypeus with three prominent, spoon-shaped 

hairs which are curved toward the rear of the head reflexa 

Each lateral border of the clypeus with four to six hairs which are spatu- 
la te but scarcely spoon-shaped and which curve forward sculpturata 

24. Upper half of the head rugulose or tuberculate; mandibles stout with their 

outer margins rather strongly convex missouriensis 

Upper half of the head reticulo-punctate; mandibles slender, their outer 
margins feebly convex pulchella 



Subgenus STRUMIGENYS F. Smith 

1. STRUMIGENYS LOUISIANAE Roger 

S. louisianae Roger, Berl. Ent. Zeitschr., Vol. 7, p. 211 (1863) 9 ; Emery, 
Zool. Jahrb. Syst., Vol. 8, p. 327 (1895) 9 ; M. R. Smith, Ann. Ent. Soc. 
Amer., Vol. 24, p. 689, pi. 1, fig. 1 (1931) 9 . 

S. unispinulosa Emery, Bull. Soc. Ent. ItaL, Vol. 22, p. 67, pi. 7, fig. 5 (1890) 
9 9. 

Type loc: Louisiana. Types: none in this country. 

Range: Florida to Texas and south into Mexico. 



2. STRUMIGENYS LOUISIANAE LATICEPHALA M. R. Smith 

S. louisianae subsp. laticephala M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, 

p. 690, pi. 1, fig. 2 (1931) 9 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 

37, No. 3, p. 548, pi. 14, fig. 52 (1947) 9 . 
Type loc: Longview, Mississippi. Types: Coll. M. R. Smith, Coll. Dept. 

Ent. A. & M. Coll. Miss. 
Range: Mississippi through the eastern Gulf States and north to the Caro- 

linas. 

It seems proper to consider laticephala as a northern race of louisi- 
anae. The two forms have a considerable area of overlap in the Gulf 
Coast region but laticephala occurs in northern stations where the 
typical form is absent. The reverse is also true, for there are as yet 
no records of laticephala from Texas, although the typical form occurs 
there. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Subgenus TRICHOSCAPA Emery 

3. STRUMIGENYS (TRICHOSCAPA) ABDITA L. G. & R. G. Wesson 

S. (C.) abdita L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 106, pi. 3, 

fig. 6 (1939) 9 . 

Typeloc: Jackson, Ohio. Type: M.C.Z., Paratypes: Coll. Wessons. 
Range: known only from the three type specimens. 



4. STRUMIGENYS (TRICHOSCAPA) ANGULATA M. R. Smith 

S. (C.) angulata M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 697, pi. 1, 

fig. 3 (1931) 9 . 
Type loc: Louisville, Mississippi. Types: Coll. M. R. Smith, M.C.Z., Coll. 

Dept. Ent. A. & M. Coll. Miss. 
Range: known only from type material. 



5. STRUMIGENYS (TRICHOSCAPA) BIMARGINATA L. G. & R. G. Wesson 

S. (C.) bimarginata L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, & 95, pi. 3, 

fig. 2 (1939) 9 . 

Type loc: Cedar Mills, Adams County, Ohio. Type: M.C.Z. 
Range: Ohio south to Alabama. 



6. STRUMIGENYS (TRICHOSCAPA) BREVISETOSA M. R. Smith 

S. (C.) dypeata var. brevisetosa M. R. Smith, Ann. Ent. Soc. Amer., Vol. 28, 

p. 215 (1935) 9 . 

Typeloc: Lucedale, Mississippi. Type: Coll. M. R. Smith. 
Range : known only from type material. 

This insect cannot be regarded as a subspecific variant of dypeata, 
for it occurs in the same area with dypeata. It appears to be quite as 
distinct as several other forms which have been given specific status 
and, until more material is available, it seems best to treat brevisetosa 
as a species. 



. . STRUMIGENYS (TRICHOSCAPA) CLYPEATA Roger 

S. dypeata Roger, Berl. Ent. Zeitschr., Vol. 7, p. 213 (1863) 9 ; Mayr, Verb. 

Zool-bot. Ges. Wien, Vol. 37, p. 571 (1887) 9 ; Emery, Bull. Soc. Ent. 

Ital., Vol. 22, p. 325, pi. 8, fig. 3 (1890) 9 ; Emery, Zool. Jahrb. Syst., 

Vol. 8, p. 328, pi. 8, figs. 21, 22 (1895) 9 9 cf . 
S. (C.) dypeata M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 699, pi. 3 



CREIGHTON: ANTS OF NORTH AMERICA 600 

fig. 9 (1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 93 

(1939) 9. 

Type loo: Louisiana. Types: none in this country. 
Range: the entire southeastern United States north to Pennsylvania and west 

to Illinois. 

There has been confusion regarding the type material of clypeata. 
This species was described by Roger from specimens taken in Louisi- 
ana. When Weber described talpa in 1934 he cited two specimens of 
clypeata in the collection of the Museum of Comparative Zoology as 
cotypes. These two insects were taken at Beatty, Pennsylvania, 
hence they are not cotypes. They seem to be a part of the series of 
specimens on which Emery based his redescription and figure of 
clypeata which was published in 1895. There is little doubt that they 
are authentically determined, since Emery had specimens of clypeata 
from Roger. But Weber's, citation is both incorrect and confusing in 
view of the general assumption that most of Roger's types no longer 
exist. 

I have removed from clypeata the varieties brevisetosa M. R. Smith, 
pilinasis Forel and laemnasis M. R. Smith. My reasons for these 
changes are discussed under the forms involved. 

8. STRUMIGENYS (TRICHOSCAPA) CREIGHTONI M. R. Smith 

S. (C.) creightoni M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 705, pi. 4, 

fig. 16 (1931) 9 . 

Type loc: Spring Hill, Mobile, Alabama. Types: Coll. M. R. Smith. 
Range: southern Alabama to eastern Tennessee. 

9. STRUMIGENYS (TRICHOSCAPA) DIETRICHI M. R. Smith 

S. (C.) dietrichi M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 696, pi. 2, 
fig. 6 (1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 93 
(1939) 9. 

Type loc: Lucedale, Mississippi. Types: Coll. M. R. Smith, Coll. Dept. 
Ent. A. & M. Coll. Miss. 

Range: Mississippi and Alabama north to Ohio. 



10. STRUMIGENYS (TRICHOSCAPA) MARGAHITAE Forel 

S. margaritae Forel, Trans. Ent. Soc. Lond., p. 378 (1893) 9 9 cf ; Emery, 

Bull. Soc. Ent, Ital, Vol. 26, pi. 1, fig. 6 (1894) 9 . 
S. (C.) margaritae M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 692, pi. 2, 

fig. 7 (1931) 9 . 



306 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Typeloc: St. Vincent, West Indies. Types: A.M.N.H., M.C.Z. 
Range: all records for this Antillean species coming from the United State: 
have been confined to Texas. 



11. STRUMIGENYS (TRICHOSCAPA) MEMBRANIFERA SIMILLIMA Emery 

S. mimbranifera subsp. simillima Emery, Bull. Soc. Ent. Ital., Vol. 22, p. 69, 

pi. 8, fig. 5 (1890) 9 . 
S. (C.) membranifera subsp. simillima M. R. Smith, Ann. Ent. Soc. Amer., 

Vol. 24, p. 693, pi. 3, fig. 10 (1931) 9 . 
S. (C.) membranifera var. marioni Wheeler, Proc. Hawaiian Ent. Soc., Vol. 8, 

No. 2, p. 276 (1933) 9 . 

Type loc: St. Thomas, Virgin Islands. Types: none in this country. 
Range: eastern Gulf States. 

There is no possible justification for Wheeler's recognition of the 
variety marioni. Wheeler set up this variety from specimens identi- 
fied as the typical simillima by M. R. Smith. These had been com- 
pared by Dr. Smith with a cotype of simillima. Dr. Wheeler had no 
cotype of simillima, but relied on topotypes as the basis for his com- 
parison. It is interesting to note Dr. Wheeler's statement in regard 
to this matter. His observation is as follows : 

'The distinguishing characters of the various forms of simillima are 
so slight that their precise taxonomic rank cannot be determined 
without additional material.' 

Since Dr. Wheeler did not hesitate to set up the varieties marioni 
and williamsi with this observation in mind, about the only thing 
that was proved by their description is the low regard which Dr. 
Wheeler had for varietal status. Dr. Smith's view is far sounder and 
I have, therefore, placed the variety marioni in the synonymy of 
simillima. 



12. STRUMIGENYS (TRICHOSCAPA) MANNI L. G. & R. G. Wesson 

S. (C.) manni L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 97, pi. 3, 

fig. 3 (1939) 9 . 
Typeloc: Sinking Spring, Pike County, Ohio. Types: M.C.Z., Coll. Wessons, 

Coll. W. S. Creighton, Coll. Wm. L. Brown, Jr. 
Range: known only from type material. 

The structure of manni is remarkably like that of ohioensis. The 
shape of the clypeus and the dentition of the mandibles is practically 
identical in the two forms. The Wessons described the anterior edge 
of the clypeus of manni as 'rather sharply truncate' but this is certainly 



CREIGHTON: ANTS OF NORTH AMERICA ou. 

not the case in the cotypes which I have examined. Both the man- 
dibles and the clypeus of manni are covered with numerous hairs 
which obscure the finer details of structure. If these parts are covered 
by some liquid (such as carbon tetrachloride) which will cut down 
the refraction caused by the hairs, a much clearer notion of their 
structure may be secured. Under such circumstances the anterior 
edge of the clypeus of manni is fully as convex as that figured for 
ohioensis by Dr. Kennedy. Since about the only notable difference 
between these two insects appears to be the number and shape of the 
erect hairs on the clypeus, it is entirely possible that manni may prove 
to be a synonym when ohioensis is better known. 

13. STRUMIGENYS (TRICHOSCAPA) MEDIALIS L. G. & R. G. Wesson 

S. (C.) medialis L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 94, pi. 3' 

fig. 1 (1939) 9 . 

Typeloc: Beaver, Pike County, Ohio. Types: M.C.Z., Coll. Wessons. 
Range: known only from type material. 

14. STRUMIGENYS (TRICHOSCAPA) MISSOURIENSIS M. R. Smith 

S. (C.) missouriensis M. R. Smith, Ann. Ent. Soc, Amer., Vol. 24, p. 701, 
pi. 4, fig. 14 (1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, 
p. 101 (1939) 9 . 

Typeloc: Columbia, Missouri. Types: M.C.Z., Coll. M. R. Smith. . 

Range: Missouri east to Ohio. 



15. STRUMIGENYS (TRICHOSCAPA) PILINASIS Forel 

S. clypeata var. pilinasis Forel, Ann. Soc. Ent. Belg., Vol. 45, p. 339 (1901) 9 . 
S. (C.) clypeata var. pilinasis M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, 

p. 700, pi. 3, fig. 12 (1931) 9 . 

Type loc: Washington, D.C. Types: none in this country. 
Range: known only from' the District of Columbia. 

So little is known about this insect that it is difficult to deal with 
it. Nevertheless, I believe that the Wessons were correct in treating 
pilinasis as a separate species in the key which they published in 1939. 
My only objection is that the Wessons did not go far enough in this 
matter. If pilinasis deserves to be separated from clypeata, the same 
treatment must be accorded to laemnasis. The peculiar clypeal pil- 
osity of the two forms is quite unlike that of clypeata. Moreover, there 
is nothing to indicate that either form can be treated as a subspecies 



oUo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

of clypeata. It may be admitted that we know extremely little about 
the range of either pilinasis or laevinasis, but we do know that both 
insects have been taken at stations within the range of clypeata. Un- 
der such circumstances it is difficult to see how either form can be re- 
garded as a subspecies of clypeata. I have treated laevinasis as a sub- 
species of pilinasis, since there is nothing in the distribution of the two 
insects that would, at present, negate this view. It is entirely pos- 
sible, however, that additional data on distribution may make it 
necessary to give specific rank to laevinasis also. 



R. Smith 



S. (C.) clypeata var. laevinasis M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, 

p. 701, pi. 3, fig. 11 (1931) V . 
Type loo: Louisville, Mississippi. Types: Coll. M. R. Smith, Coll. Dept. 

Ent. A. & M. Coll. Miss. 
Range: known only from type material. 



17. STEUMIGENYS (TRICHOSCAPA) OHIOENSIS Kennedy & Schramm 

<S. ohioensis Kennedy & Schramm, Ann. Ent. Soc. Amer., Vol. 26, p. 98, fig. 3 

(1933) 9. 

Type loc : Tuppers Plains, Meigs County, Ohio. Types : Coll. C. H. Kennedy. 
Range: known only from Ohio. 



18. STRUMIGENYS (TRICHOSCAPA) ORNATA Mayr 

S. ornata Mayr, Verh. Zool-bot. Ges. Wien, Vol. 37, p. 571 (1887) V ; Emery, 

Bull. Soc. Ent. Ital., Vol. 22, pi. 8, fig. 2 (1890) 9 ; Emery, Zool. Jahrb. 

Syst., Vol. 8, p. 325, pi. 8, fig. 20 (1895) 9 . 
S. (C.) ornata M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 695, pi. 2, fig. 5 

(1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 92 (1939) 9 . 
Type loc: Washington, D.C. Types: U.S.N.M. 
Range: District of Columbia south to the eastern Gulf States and west to 

Ohio. 



19. STRUMIGENYS (TRICHOSCAPA) PERGANDEI Emery 

S. pergandei Emery, Zool. Jahrb. Syst., Vol. 8, p. 326, pi. 8, figs. 17, 18 (1895) 

9 9d". 
S. (C.) pergandei M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 698, pi. 1, 

fig. 4 (1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 92 

(1939) 9. 



CREIGHTON: ANTS or NORTH AMERICA 309 

Type loo: District of Columbia (by present restriction). Types: U.S.N.M., 

M.C.Z., A.M.N.H. 
Range: northeastern United States and southern Ontario south to Virginia 

and west to Iowa. 

20. STRUMIGENYS (TRICHOSCAPA) PULCHELLA Emery 

S. pulchella Emery, Zool. Jahrb. Syst, Vol. 8, p. 327, pi. 8, fig. 19 (1895) 9 . 

S. (C.) pulchella M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 702, pi. 4, 

fig. 13 (1931) 9 ; 'L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 100 

.(1939) 9. 

Type loo: Washington, D.C. (by present restriction). Types: U.S.N.M. 
Range: southern New York west to Iowa and south to the eastern Gulf 
States. 

21. STRUMIGENYS (TRICHOSCAPA) REFLEXA L. G. & R. G. Wesson 

S. (C.) reflexa L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 102, pi. 3, 

fig. 4 (1939) 9 . 
Type loc: Jackson, Ohio. Type: M.C.Z., Paratypes: Coll. Wessons, 

A.M.N.H., Coll. W. S. Creighton. 
Range: known only from type material. 

22. STRUMIGENYS (TRICHOSCAPA) ROHWERI M. R. Smith 

S. (C.) rohweri M. R. Smith, Ann. Ent. Soc. Amer., Vol. 28, p. 214 (1935) 9 . 
Type loc: Holly Springs, Mississippi. Types: U.S.N.M., Coll. M. R. Smith. 
Range: known only from type material. 



23. STRUMIGENYS (THICHOSCAPA) HOSTHATA Emery 

S. rostrata Emery, Zool. Jahrb. Syst., Vol. 8, p. 329, pi. 8, fig. 23, 24 (1895) 9 . 
8. (C.) rostrata M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 704, pi. 2, 

fig. 8 (1931) 9 ; L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 99 

(1939) 9. 
-S. (T.) rostrata M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 584, 

pi. 14, fig. 54 (1947) 9 . 
Type loc: Washington, D.C. Types: U.S.N.M., M.C.Z., A.M.N.H., Coll. 

W. S. Creighton. 
Range: New Jersey south to the eastern Gulf States and west to Ohio. 

In 1931 Dr. M. R. Smith regarded the range of rostrata as covering 
much of the United States. This view was based on a record of this 
species from Claremont, California. Since all the other records of 
this species come from east of the Mississippi River, Dr. Smith's 



310 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

conclusion appears very doubtful. It is more likely that the pres- 
ence of rostrata in California may be due to its introduction into that 



24. STKUMIGENYS (TKICHOSCAPA) SCULPTURATA M. R. Smith 

S. (C.) sculpturata M. R. Smith, Ann. Ent. Soc. Amer., Vol. 24, p. 706, pi. 4, 

fig. 15 (1931) 9 . 
Type loc: Aberdeen, Mississippi. Types: Coll. M. R. Smith, Coll. Dept. 

Ent. A. & M. Coll. Miss. 
Range: Mississippi to southern New England. 



25. STRUMIGENYS (TRICHOSCAPA) TALPA Weber 

S. (C.) talpa Weber, Psyche, Vol. 41, p. 63, fig. 1 (1934) 9 . 

S. (C.) venatrix L. G. & R. G. Wesson, Psyche, Vol. 46, No. 2, p. 103, pi. 3, 

fig. 5 (1939) 9 . 

Type loc: Herod, Illinois. Type: Coll. 111. Nat. Hist, Soc. 
Range: southern Alabama north to Illinois and Ohio. 

Through the courtesy of Mr. W. L. Brown, Jr., I was able to com- 
pare the type of talpa with those of venatrix. Mr. Brown is of the 
opinion that the two insects are the same, and I agree with him. 
There can be no doubt that the Wessons were misled by Dr. Weber's 
figure of the head of talpa, for this figure gives the impression of a 
much wider head than is actually the case. It may be recalled that 
Dr. Weber described the clypeal hairs of talpa as 'narrow-squamose'. 
The hairs, particularly those at the margin of the clypeus, are slightly 
flattened and thickened distally. But this flattening is not great 
enough to show under ordinary magnification, and it is only under 
very high magnification that the clypeal hairs of talpa appear to be 
somewhat squamose. 

Genus CYPHOMYRMEX Mayr 
(Plate 40, figures 1-4) 

The great majority of the species which belong to the genus Cypho- 
myrmex are distributed throughout tropical regions in Central Am- 
erica, South America and the Antilles. The two species which occur 
in the United States are found only in areas close to our southern 
boundary. One of these, C. wheeled, is easy to handle, for it is marked 
by very distinct morphological characters and throughout its rather 
circumscribed range it has, apparently, produced no subspecific vari- 
ants. One could wish that a similar clarity prevailed in the case of 



CREIGHTON: ANTS OF NORTH AMERICA dii 

rimosus, a single form of which occurs within our borders. But this 
widespread and highly variable species has been a focal point for er- 
rors and contradictions since the time of its description almost a cen- 
tury ago. So many myrmecologists have expressed opinions on the 
status of rimosus and its subspecies minutus that it is easy to become 
confused and misconstrue what has been said. This result has oc- 
curred in Dr. Weber's 1940 revision of Cyphomyrmex. In this re- 
vision, Dr. Weber proposes to synonymize the subspecies minutus 
with the typical rimosus and to show that his proposal has the sup- 
port of other myrmecologists, he makes the following observation: 

"Both Wheeler and Forel believed Mayr's minutus to be a synonym 
of rimosus, although they frequently recorded the West Indian Cypho- 
myrmex as rimosus ssp. or var. rimosus." 

I find this statement disturbing, for it is largely contrary to fact. 
At no time did Wheeler ever propose to regard minutus as a synonym 
of rimosus, and there is abundant printed evidence to show that he 
considered the two as separate forms to the end of his life. In Forel's 
case there is more justification for Dr. Weber's statement. When 
Forel included minutus in the synonymy of rimosus in 1899, the 
treatment was that proposed six years earlier in Dalla Torre's Cata- 
logue. In 1899 Forel was obviously unaware that Emery had pub- 
lished data in 1894 which made such a treatment impossible. As I 
shall show in the sequel, Forel was never fully acquainted with the 
nature of the rimosus-minutus problem. As a result, his judgement on 
this matter was of very limited value. I am sorry to say that much 
the same considerations apply to Dr. Weber's view. He, like Forel, 
has neglected the importance of certain observations made upon 
rimosus and minutus by Carlo Emery. In the following paragraphs I 
have traced the steps in the rimosus-minutus problem in the hope 
that a full account of this matter may enable myrmecologists to judge 
the merits of the various contentions more accurately. 

In 1851 Spinola published the description of an ant which he called 
Cryptocerusl rimosus. The specimens on which he based this species 
were said to have come from Para, Brazil. Spinola's description is 
very imperfect and it may be doubted that anyone could have recog- 
nized the insect from it. Certainly Frederick Smith could not for, 
although he listed Spinola's species in 1853, he redescribed it as 
Meranoplus difformis nine years later. In that same year (1862) 
Mayr set up the genus Cyphomyrmex. As a basis for this genus 
Mayr had specimens, taken in Cuba, to which he gave the specific 
name minutus. This brought an immediate response from Roger 
who, in the following year, denied the validity of Cyphomyrmex, 
designated minutus as a synonym of Smith's difformis (which Roger 



612 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

spelled 'deformis') and shifted that species to the genus Cataulacus. 
While Mayr was willing to accept Roger's specific synonymy, he 
would not agree to sink the genus Cyphomyrmex. Thus, for many 
years, minuius appeared in myrmecological literature as Cypho- 
myrmex deformis. 

In 1884 Forel described a species of Cyphomyrmex, which he called 
steinheili, from material taken in the Lesser Antilles. There can be 
no doubt that at that time Forel was unaware of the nature of Mayr's 
minutus for, as Mayr was able to show later, the two insects are 
identical. In 1893 Emery was invited to examine the collection of 
ants made by Spinola, which had been deposited in the Zoological 
Museum of Turin. From the brief paper which Emery published as a 
result of this examination it seems clear enough that a considerable 
part of his interest in Spinola's collection lay in the fact that it con- 
tained specimens identified by Latreille and Klug. Spinola's own 
species were all too plainly in bad shape. They were poorly, and in 
some cases erroneously, labelled. Thus the type of Spinola's Cos- 
macetus omalinus, which proved to be a synonym of Typhlopone ful- 
vus, bore a locality label marked Para, Brazil. This is an obvious im- 
possibility, since fulvus is endemic to North Africa and Asia minor. 
Emery could find no specimens labelled Cryptocerus? rimosus for the 
space so marked in the cabinet was bare. He found, however, some 
specimens labelled Myrmica rimosus, apparently without any other 
data attached, which he regarded as the "same thing" (the phrase 
Emery employed is "la stessa cosa"). It is possible to argue that 
Emery could not be sure that the specimens of Myrmica rimosus were 
the same as those from which Cryptocerus? rimosus was described. 
But if this stand is taken, then rimosus must be relegated to the limbo 
of unrecognizable species and the name replaced by difformis. Con- 
versely, if we are to continue to use the name rimosus, we must not 
only agree with Emery's association but also accede to his definition 
of the characteristics of that species. For of the various myrmecolo- 
gists who have expressed opinions as to the nature of the typical 
rimosus, Emery and Emery alone, has examined the only specimens 
which may be regarded as authentic. 

Emery not only examined the Spinola specimens carefully but also 
managed to secure a male from the series which he took home for 
further examination and comparison with material in his own col- 
lection. As a result of these studies Emery published in the following 
year (1894) an arrangement of the rimosus complex which greatly 
clarified the matter. In this arrangement difformis was made a syn- 
onym of rimosus. Forel's steinheili became a synonym of minutus, 
which was made a subspecies of rimosus. In addition, Emery de- 



CREIGHTON: ANTS OF NORTH AMERICA 616 

scribed two new variants, the subspecies transversus and a variety 
which he called fuscatus. To authenticate this arrangement Emery 
presented several structural differences by which the typical rimosus 
could be separated from the subspecies minutus. In the worker of 
the typical rimosus the second node of the petiole is only a little 
broader than long and the teeth of the thorax are strong and acute, 
particularly the lateral pair on the pronotum. In the subspecies 
minutus the second node of the petiole is almost half again as broad 
as long and noticeably broader than the preceding joint. The teeth 
or tubercles of the thorax are smaller and less acute than those of the 
typical form, particularly those at the rear of the epinotum, which 
are so reduced as to be scarcely noticeable. These distinctions appear 
to be clear enough but it is never easy to reestablish a form which 
has long been treated as a synonym and minutus had been thus ob- 
scured for more than a quarter of a century. Perhaps this is why, 
when Forel dealt with rimosus in the formicid section of the Biologia 
Centrali Americana (1899), he made no clear distinction between the 
typical form and the subspecies minutus. Nor was the situation any 
better in. 1901, when Forel redescribed the subspecies transversus 
under the name olindanus. Since transversus is a very distinct form 
and since Emery described it not only in the same paper but on the 
same page which carried his diagnostics for minutus, it seems clear 
enough that Forel had made little effort to benefit by Emery's studies. 
But Forel's refusal to recognize minutus, or his inability to do so, by 
no means invalidates the basis on which that subspecies rests. Emery's 
stand is a sound one and Wheeler was perfectly aware of this, for he 
repeated the substance of Emery's observations in his 1907 study. 
It was in this paper that Wheeler stated that he had some doubt as 
to whether minutus deserved to rank as a subspecies. This state- 
ment appears to be the point of departure from which Dr. Weber ar- 
rived at the very different pronouncement quoted in an earlier para- 
graph. During the next thirty years, Wheeler cited minutus on many 
occasions but, except for one time when he referred to it as a variety 
(1913), he invariably treated it as a subspecies of rimosus. 

I have undertaken this involved presentation because I cannot 
agree with Dr. W r eber that minutus is a synonym of the typical rim- 
osus. I am more than ready to agree that the same form of this in- 
sect is widely distributed throughout the Antilles and the tropical 
portions of continental America. But where Dr. Weber regards this 
widely distributed form as the typical rimosus, I believe that it is 
actually the subspecies minutus. There seems to be little possibility 
for error in this matter, since the form referred to is the only one which 
occurs in Cuba, from which island the types of minutus came. Yet 



314 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Dr. Weber utilizes this fact as his principal reason for synonymizing 
the two forms. Since he can see no difference of any significance be- 
tween the insular specimens (which are obviously minutus) and those 
from the continent, which he regards as the typical rimosus, the two 
must be synonyms. But Dr. Weber gives no reason why the common 
continental form must be regarded as the typical rimosus. Emery 
stated clearly that the teeth on the thorax of that form are well- 
developed, yet in Dr. Weber's plate the thorax of the insect which he 
regards as the typical rimosus is the least spinose of any figured and 
corresponds remarkably to Emery's description of the thorax of 
minutus. The same may be said for the characteristics of the "typical 
rimosus" which Dr. Weber has given in his key. I repeat that I believe 
that Dr. Weber's "typical rimosus" is actually minutus and I further 
believe that he, in company with other myrmecologists, has either 
not seen the typical rimosus or else has assigned it to some other sub- 
species. For there seems to be no end to the array of continental 
variants which have been described as subspecies of rimosus. Several 
of these with well-developed, acute thoracic teeth (salvini, trinatatis, 
dentatus etc.) appear to be very similar to the insect that Emery de- 
scribed as the typical rimosus. Finally, I believe that instead of syn- 
onymizing minutus with rimosus, it may subsequently prove to be a 
separate species. For it is clear that all of the present welter of sub- 
species assigned to rimosus cannot properly be treated as such. Since 
two or more may occur in the same stations, the possibility for treat- 
ing them as geographical races is considerably limited. No doubt 
there are a number of true geographical races present in the complex 
but they cannot all be assigned to the same species. I would venture 
the opinion that there are several sibling species involved in the 
rimosus complex as it is constituted at present and when the situation 
is more fully resolved, minutus will be found to be one of them. In 
this connection it is of interest to observe that in 1925 Wheeler pub- 
lished the statement that in his opinion the subspecies transversus and 
salvini might properly be regarded as distinct species. Since the ele- 
vation of minutus to specific rank will necessitate a broad revaluation 
of the rimosus complex, I have continued to treat this insect as a sub- 
species in this work. 

In the case of most attine genera the habit differences between 
species belonging to the same genus are usually slight. Cyphomyrmex, 
on the other hand, possesses a number of species whose habits differ 
to an extent which makes generalization difficult. It is possible, how- 
ever, to note certain similarities which seem to prevail in most of the 
species. Much of the data presented below is taken from Wheeler's 
1907 monograph of the Attini. The colonies of Cyphomyrmex are 



CREIGHTON: ANTS OF NOETH AMERICA olo 

invariably small, rarely consisting of more than two hundred individ- 
uals and often of a much smaller number. The larger colonies usually 
possess two or three queens. The ants are slow of movement, very 
timid and readily feign death if disturbed. According to Wheeler, 
the females feign death as readily as the workers but the males are 
less apt to do so. The nests are usually constructed under some cov- 
ering object such as a stone, a small log or a piece of wood. Both pas- 
sages and chambers are less neatly built and more irregular than those 
of other attine groups. The passages and the fungus chambers as 
well, may be built directly against the lower surface of the covering 
object or sunk a few centimeters in the soil below the covering object. 

There is usually a single nest opening at one side of the covering ob- 
ject and this opening is sometimes surrounded by an obscure crater of 
excavated soil. The various species appear to grow distinctly differ- 
ent kinds of fungi and there is little uniformity as to the kinds of ma- 
terial on which the garden is grown. Thus the fungus garden of 
wheeleri consists of a glistening, white mycelium which is nourished 
with slivers of vegetable tissue thrust directly into the garden without 
previous trituration. That of rimosus subsp. minutus does not appear 
to be a mycelium at all but consists of isolated clumps of bromatia. 
This fungus is grown on collected caterpillar droppings which are 
heaped in a small pile and kept extremely moist. In some nests the 
droppings are placed on a small dead leaf or flattened pebble which 
may prevent the moisture which covers them from draining into the 
soil below. The brood is not placed in the fungus garden but piled 
to one side of it. In both wheeleri and minutus the fungus garden lies 
on the floor of the chamber but this practice is not uniform through- 
out the genus for Weber (1940) has shown that in columbianus the 
fungus garden is suspended from a root. Weber has also presented 
evidence to show that the female of that species leaves the nest to 
forage for material on which the original garden is grown. This im- 
portant observation is the second report of such activity on the part 
of a nest founding attine female. It may be recalled that Cole in 1939 
published an account of similar behavior in the female of Trachy- 
myrmex septentrionalis subsp. seminole. 

It is my opinion that Wheeler's variety comalensis is a synonym 
of minutus. It is clearly related to that subspecies rather than to the 
typical rimosus both in the structure of the petiolar nodes and the 
character of the thoracic projections. About the only feature by which 
the two might be distinguished is the color of comalensis, which ap- 
pears to be more uniform than is of ten the case with that of the colonies 
of minutus. But it should be noted that there is no difference in the 
coloration of comalensis and that of the darker individuals present in 



316 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

the colonies of minutus. I consider this very slight and probably in- 
constant difference as insufficient to justify separate status for comal- 
ensis. If this interpretation is correct, there are only two members of 
the genus Cyphomyrmex which occur in the United States, the 
species wheeleri and rimosus subsp. minutus. The two may be sepa- 
rated as follows: 

Key to the species of Cyphomyrmex 

Tips of the antennal scapes reaching but not surpassing the posterior cor- 
ners of the head; node of the petiole with two rather slender teeth on its dor- 
sal surface; length 2-2.5 mm wheeleri 

Tips of the antennal scapes surpassing the posterior corners of the head by 
an amount approximately equal to their greatest diameter; node of the petiole 
without teeth on its dorsal surface; length 1.8-2 mm. .rimosus subsp. minutus 



1. CYPHOMYEMEX KIMOSUS MINUTUS Mayr 

Cyphomyrmex minutus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 691 

(1862) 9. 

Cataulacus deformis Roger, Berl. Ent. Zeitschr., Vol. 7, p. 210 (1863) 9 cT. 
Cyphomyrmex deformis Mayr (part), Verh. Zool-bot. Ges. Wien, Vol. 37, 

p. 558 (1887) 9 9 cf. 

C. rimosus subsp. minutus Emery, Bull. Soc. Ent. ItaL, Vol. 26, p. 225 (1894) 
9 <f; Wheeler, Bull. Amor. Mus. Nat. Hist., Vol. 21, p. 106, figs. N, O 

(1905) 9 ; Wheeler, Ibid., Vol. 23, p. 722 (1907) 9 cf; M. R. Smith, Amer. 

Mid. Naturalist, Vol. 37, No. 3, p. 586, pi. 15, fig. 55 (1947) 9 . 
C. rimosus Forel, Trans. Ent. Soc. Lond., p. 374 (1893); Forel, Biol. Centrali 

Amer. Hym., Vol. 3, p. 40 (1899); Weber, Revista Entomol., Vol. 11, 

p. 410, figs. 3, 10 (1940) 9 (nee rimosus Spinola). 
C. rimosus var. comalensis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 

719, pi. 49, fig. 1 (1907) 9 9 c?. 

C. steinheili Forel, Bull. Soc. Vaud. Sci. Nat. (2) Vol. 20, p. 368 (1884) 9 . 
Type loo: Cuba. Types: none in this country. 
Range: widely distributed throughout the Antilles and the portions of the 

continents which adjoin the Gulf of Mexico and the Caribbean Sea. In 

the United States the insect is found only in southern Florida and the 

southern part of Texas. 



2. CYPHOMYKMEX WHEELERI Forel 

C. wheeleri Forel, Mitt. Schweiz. Ent. Ges., Vol. 10, p. 282 (1900) 9 9 ; 
Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 527, pi. 49, fig. 2 (1907) 
9 9 d 1 ; Weber, Revista Entomol., Vol. 11, p. 409 (1940) 9 . 

Type loc: Austin, Texas. Types: M.C.Z. 

Range: south central to western Texas and southern California. 



CREIGHTON: ANTS OF NOKTH AMERICA 317 

In 1907 Wheeler believed that the range of this species extended 
westward from Texas to California and also entered northern Mex- 
ico. Although this supposition is entirely logical, there are still no 
published records to support it. On the contrary, much collecting in 
southern Arizona has seemed to show that wheeleri is absent or ex- 
ceedingly rare in that region. The distributional characteristics of 
wheeleri are likely to remain problematical until more is known of the 
ants of the northern provinces of Mexico. It is clear, however, that 
wheeleri is much more xerophilous than minutus and this must cer- 
tainly have a bearing on its distribution. 



Genus MYCETOSORITIS Wheeler 

In the present work I have accorded generic status to Mycetoso- 
ritis. It seems that no other course is possible if we are to strive for 
consistency in the treatment of the attine genera. I have explained 
elsewhere (see the discussion under the genus Atta) that these genera 
intergrade to a much greater extent than is commonly the case in 
other formicid groups. It need, therefore, occasion no difficulty 
that Mycetosoritis is plainly transitional between Trachymyrmex 
and Cyphomyrmex. When Wheeler described Mycetosoritis hartmanni 
in 1907 he made it a subgenus of Atta. Later he decided that it was 
more properly considered a subgenus of Trachymyrmex. It appeared 
as a subgenus in Emery's expanded version of the genus Cypho- 
myrmex and, since Emery also included Trachymyrmex as a subgenus 
of Cyphomyrmex, his arrangement showed a congruous relation be- 
tween the three groups involved. But while neither of the above 
authorities saw fit to treat Mycetosoritis as a genus, both advocated 
the recognition of other attine genera on structural distinctions which 
are little if any better than those which mark Mycetosoritis. If 
Acromyrmex and Trachymyrmex are to be treated as genera, it is no 
more than consistent to accord generic status to Mycetosoritis also. 
Moreover such a treatment appears to be the only one which will re- 
lieve the problem of what to do with Mycetosoritis, for as long as it 
remains a subgenus it must be assigned either to Trachymyrmex or 
to Cyphomyrmex. But its inclusion in either genus is unsatisfactory, 
since it breaks down what might otherwise be rather clear cut generic 
diagnostics. For in the worker of Trachymyrmex the antennal lobes, 
though large, are rounded in front and do not project forward above 
the anterior border of the clypeus. The body hairs are erect and 
curved or hooked at the end and many of them, especially those on 
the head and gaster, arise from small but distinct tubercles. The 



318 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

thorax bears a number of well-developed spines which are usually 
slender and only rarely have the form of conical teeth. In Cypho- 
myrmex the antennal lobes project well forward, so that their pointed 
tips overhang the anterior border of the clypeus. The body hairs are 
appressed, flattened and usually scale-like, never curved or hooked. 
These hairs very rarely arise from tubercles. The thorax is variously 
ornamented with laminae, ridges or bosses which may have sharp 
tips but these tooth-like projections rarely resemble spines, although 
the term is often applied to them. In Mycetosoritis the antennal 
lobes are large and overhang the clypeus. The thorax bears short, 
pointed teeth or connules. The suberect body hairs are curved and 
those on the gaster arise from tubercles, although there are com- 
paratively few tubercles elsewhere on the body. To include such an 
obviously transitional species in either genus weakens the distinctions 
by which they may be separated. If we wish to maintain Trachy- 
myrmex and Cyphomyrmex as separate genera, the safest plan is to 
give Mycetosoritis full generic rank for, if it is made a subgenus of 
Cyphomyrmex, there is no clear break between Cyphomyrmex and 
Trachymyrmex. As far as habits are concerned Mycetosoritis might 
be included in either genus but does not fit either overly well. It con- 
structs a suspended fungus garden (a habit more frequently met with 
in Trachymyrmex) which is grown on untriturated plant material (a 
characteristic often met with in Cyphomyrmex). But this plant 
material has a unique character for it consists entirely of the withered 
anthers of flowers. In this respect Mycetosoritis corresponds to no 
other known attine and, if this unusual choice of material is a con- 
sistent one, Mycetosoritis is marked by a distinct habit pattern of 
its own. 

Of the two species of Mycetosoritis which have been described, 
only one, M. hartmanni, occurs in the United States. 



1. MYCETOSORITIS HARTMANNI Wheeler 

Atta (M.) hartmanni Wheeler, Bull. Amer. Mus. Nat. Hist,, Vol. 23, p. 714, 

pi. 49, figs. 6, 7 (1907) V 9 d>. 
Cyphomyrmex (M.) hartmanni Emery, Ann. Soc. Ent. Belg., Vol. 57, p. 251 

(1913); M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 588, pi. 

15, fig. 56 (1947) 9 . 

Type loc: Montopolis and Delvalle, Texas. Types: M.C.Z. 
Range : known only from type material. 



CREIGHTON: ANTS OF NORTH AMERICA 



Genus TEACHYMYRMEX Forel 
(Plate 41, figures 1-4) 

There are several reasons why the North American representatives 
of the genus Trachymyrmex offer exceptionally good material to those 
interested in the biology of the fungus-growing ants. Although their 
colonies are far less spectacular than the huge formicaries of the 
genus Atta, their range in America north of Mexico is incomparably 
greater. This is largely because of the widespread distribution of 
septentrionalis. a species whose range extends from Texas to southern 
New York. Throughout much of this range septentrionalis is sur- 
prisingly abundant but it is often overlooked since it is a timid and 
unaggressive species with rather inconspicuous nesting habits. But 
here again these characteristics facilitate observation. There is none 
of the difficulty which one encounters with a large Atta colony where 
the inhabitants are usually so active and pugnacious that close ob- 
servation is unpleasant or impossible without first killing off most 
of the inhabitants of the nest. 

The habits of our species of Trachymyrmex, particularly septen- 
trionalis, have been repeatedly observed. As early as 1880, both 
Morris and McCook had published observations on the habits of 
septentrionalis but these early accounts contained many inaccuracies. 
Neither of these observers recognized the true nature of the fungus 
gardens and it was not until 1896 that these were correctly inter- 
preted by Swingle. Two very extensive accounts of the biology of 
these insects were published by Wheeler in 1907 and 1911. The most 
recent publication is that of Cole, who added some interesting data 
in a paper which appeared in 1939. It is impossible here to do more 
than present a summary of the material carried in the above papers. 

All the species of Trachymyrmex which occur in the United States 
form small colonies. In T. arizonensis, whose nests are the largest of 
any of our species, there may be as many as a thousand workers 
present. But the number is usually much smaller and many of the 
nests of septentrionalis and turrifex consist of only a few dozen indi- 
viduals. These ants are decidedly timid and rather slow of movement. 
The foraging workers are apt to feign death if disturbed and even 
when the nest is broken open they usually make little attempt to re- 
sist the intruder. The form of the nest is remarkably constant con- 
sidering the widely different situations in which they are built. Al- 
though the soil at the surface of the ground may be friable and crumbly, 
the chambers which contain the fungus gardens are always constructed 
in hard packed soil, sand or gravel. The chambers, which are roughly 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



ovoid and at most a few inches in diameter, are connected by un- 
branched passages. If the nests are constructed in areas where trees 
or shrubs are growing, each of the chambers contains one or more 
rootlets of these plants which have been left intact during the ex- 
cavation and which serve as an anchorage to which the fungus garden 
is originally attached. In some cases these roots are pendant from the 
roof of the chamber; in others they run through the chamber from 
side to side. If plant roots are not present, as is often the case when 
the nests are established in open desert areas, the fungus garden is 
attached directly to a stone in the roof of the chamber. The fungus 
garden is grown on comminuted caterpillar excrement, or plant tissue 
or a mixture of the two. The nest is often surmounted by various 
types of excavated or built up structures. In septentrionalis there is 
usually a crescent-shaped mass of sand about the nest opening and in 
the center of this partial crater there may be a smaller circle of bits of 
vegetable detritus. In turrifex a chimney one or two inches high and 
constructed of earth particles and vegetable detritus usually sur- 
mounts the nest opening. Wheeler was of the opinion that this chim- 
ney was a specific pecularity found only in turrifex but Cole has shown 
that similar structures are occasionally built by septentrionalis. The 
nests of the desert-dwelling species usually lack any surmounting 
structure, although the opening may be surrounded by bits of old, 
discarded fungus gardens. The nest openings are often closed by the 
ants during periods of heat and drought, apparently to conserve mois- 
ture in the chambers containing the fungus gardens. 

The colony may contain one or several dealated females. The num- 
ber of queens present appears to have little to do with the size of the 
colony for the small colonies of turrifex regularly contain several 
queens. According to Cole the nest-founding female of septentrionalis 
subsp. seminole, after constructing a single, small chamber, forages 
outside the nest for materials on which the original fungus garden is 
grown. If this is true of the other species of Trachymyrmex it affords 
a significant habit difference between this genus and Atta. For in 
Atta sexdens, and presumably in the other species as well, the female 
practices the claustral type of nest-founding and nourishes the first 
fungus garden with her own excrement and broken and macerated 
eggs taken from the brood. 

The following key has been modified from the key to the genus 
which was published by Wheeler in 1911. 

Key to the species of Trachymyrmex 

1. Preorbital carina not curved mesially and not crossing the antennal scrobe 
but continued backward to the posterior corner of the head 2 



CREIGHTON: ANTS or NORTH AMERICA 6Zi 

Preorbital carina curved inward and crossing or at least entering the an- 
tenna! scrobe and not extending to the posterior corner of the head 3 

. Color ferrugineous; gaster with a feebly developed median dorsal im- 
pression and lateral ridges; length 3-3.75 mm turrifex 

Color brownish yellow; gaster without median dorsal impression or lateral 
ridges; length 2.5-2.8 mm turrifex subsp. caroli 

3. Lateral projections of the promesonotum forming rough, rather flattened 

cones, distinctly not spine-like desertorum 

Humeral angles of the pronotum with distinct spines which are longer 
than those on the remainder of the promesonotum, at least some of the 
latter spine-like, not conical 4 

4. Posterior corners of the head each with a cluster of rather slender tuber- 

cules with blunt tips and all of about the same length arizonensis 

Posterior corners of the head each with one prominent bidentate tubercle 
and several shorter and smaller tubercles which are not bidentate 5 

5. Color brownish yellow; surface of the body rather smooth and slightly 

shining; spines slender septentrionalis 

Color ferrugineous to blackish brown; surface of the body distinctly gran- 
ular and opaque; spines stouter 6 

6. Length 3-3.5 mm.; infuscation of the front and gastric dorsum feeble. . . . 

septentriorudis subsp. obscurior 

Length 3.5-4 mm.; infuscation of the front and gastric dorsum distinct. . 

septentrionalis subsp. seminole 



1 . TRACHYMYRMEX ARIZONENSIS (Wheeler) 

Atta (T.) arizonensis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 710, 
pi. 49, figs. 9, 10 (1907) 9 cf ; Wheeler, Psyche, Vol. 18, p. 93, fig. 1 
(1911) 9. 

Type loc: Huachuca Mts., Arizona. Types: M.C.Z., A.M.N.H. 

Range: known only from the Huachuca Mountains where it occurs at eleva- 
tions between 5000 and 6000 feet. 



2. TRACHYMYHMEX DESERTORUM (Wheeler) 

Atta (T.) desertorum Wheeler, Psyche, Vol. 18, p. 98, fig. 2 (1911) 9 . 
Type loc: Carnegie Desert Lab., Tucson, Ariz. Types: M.C.Z. 
Range : known from type material only. 



3. TRACHYMYRMEX SEPTENTRIONALIS (McCook) 

It is necessary to use considerable caution in evaluating some of 
the variants described by Wheeler as belonging to this species. He 
himself was by no means satisfied as to the validity of the varieties 
irrorata and crystallina at the time when he described them. The 



dzz BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

characteristic which distinguishes both these forms is the presence of 
small granules or crystals on the surface of the integument. Wheeler 
described the crystals and granules as a layer covering the surface 
uniformly but this is certainly not correct. I have examined the type 
specimens carefully and experimented with some which Dr. Wheeler 
gave me many years ago. In order to appreciate the actual disposi- 
tion of the crystals or granules it is necessary to use a very high mag- 
nification and illuminate the surface obliquely. If this is done the 
crystals or granules appear as regularly spaced, minute, white dots 
projecting above the surface. Their appearance very strongly suggests 
that they are caps of foreign material sitting on the tops of small pro- 
jections from the surface of the chitin. It may be recalled that Wheeler 
attempted to dissolve the granules by immersing the specimens in 
sodium hydroxide. This treatment failed to produce any change and, 
strangely enough, Wheeler concluded that the accretions were prob- 
ably of a fatty consistency "apparently analogous to the waxy secre- 
tions covering the bodies of senescent dragon flies ". If these ac- 
cretions are waxy, it is hard to understand why they were unaffected 
by the sodium hydroxide bath but this result would be expected if 
they are calcareous or alkaline in character. That they are of this 
nature seems to be clear, for if a dilute solution of acetic acid is brushed 
onto the surface of the insect, it dissolves the accretions in a very 
short time. It is then possible to see that the surface of the chitin be- 
tween the piligerous tubercles is not uniformly granulose but is thrown 
up into very tiny sub tubercles at regular intervals. The accretions 
form a cap on top of the subtubercles. It may be added that the same 
subtubercles are present in all forms of septentrionalis (and other species 
as well) and they frequently carry crystalline deposits at their tips. 
The type series of the subspecies seminole contains many specimens 
in which this condition occurs. About all that can be said for the 
varieties crystallina and irrorata is that they are more uniformly en- 
crusted than is ordinarily the case. In my opinion this condition is 
not due to a temporary physiological condition, or to the age of the 
specimen as Wheeler supposed, but simply to the wetting of the in- 
sects by soil water heavily charged with calcium or alkaline salts. 
When such water dries, the dissolved salts are deposited on the sur- 
face of the body. The initial deposition appears to cover the entire 
surface but later this wears away, remaining last of all on the tips of 
the small subtubercles. The bluish bloom which Wheeler observed 
in several of the ergatotypes of arizonensis, and which he attributed 
to the age of the specimens, is due to this cause. His specimens were 
taken during a period of drought when some of the nest chambers were 
dust dry. Under such circumstances only an occasional worker would 



CREIGHTON: ANTS OF NORTH AMERICA dZd 

have retained the deposit from the last wetting. In the late summer 
of 1932 I collected many colonies of arizonen.su in the type locality 
just after a period of heavy rainfall. The great majority of the workers 
were completely covered with a very heavy bloom and in certain col- 
onies the entire population was so colored. This crystalline deposit 
could be readily removed by weak acids, as described above, which 
restored the ordinary color and surface texture to the specimens thus 
treated. To return to the varieties crystallina and irrorata, there is 
absolutely no basis on which these forms can be recognized and I pro- 
pose to regard both as synonyms of the typical septentrionalis. 

The variety vertebrata presents a different problem. This is a 
slightly smaller and darker variant of the typical septentrionalis. If 
it had come from a more southern station, say southwestern Virginia 
or eastern Tennessee, it could pass for an intergrade between the 
typical septentrionalis and the subspecies obscurior. But unfortunately 
it was taken at Lakehurst, N.J., only ten miles from Toms River, 
the type locality of the typical form. There is nothing to indicate 
that there is any difference, either ecological or geographical which 
would distinguish vertebrata from the typical septrentionalis. Since 
the slight structural differences which separate the two are assuredly 
not great enouj ' 

best to treat vertebrata as a nest variety of no significance and reduce 
it to a synonym of the typical form. Wheeler's varieties obscurior 
and seminole, on the other hand, appear to be geographical races. 
The former occurs in Texas and the south central states. The latter 
is widely distributed in Florida, the eastern Gulf states and the Caro- 
Jinas. I would, therefore, arrange the septentrionalis complex as follows: 

T. septentrionalis McCook 

= var. vertebrata Wheeler 
subspecies obscurior Wheeler 
= var. irrorata Wheeler 
= var. crystallina Wheeler 
subspecies seminole Wheeler 

There follows the synonymy of Trachymyrmex septentrionalis 
McCook: 

Atta septentrionalis McCook, Proc. Acad. Nat. Sci. Phila., p. 359 (1880) 9 
A. (T.) septentrionalis Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 706, 

pi. 49, fig. 4 (1907) 9 9 d 1 ; Wheeler, Jour. N. Y. Ent. Soc., Vol. 19, 

p. 245 (1911) 9 9. 

A. (T.) septentrionalis var. vertebrata Wheeler, Ibid., Vol. 19, p. 246 (1911) 9 9 . 
A. (Acromyrmex) tardigrada Forel, Bull. Soe. Vaud. Sci. Nat., Vol. 20, p. 91 

(1884) 9 9 cf. 



o/4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Type loc: Island Heights, Toms River, New Jersey. Types: none known to 
exist. 

Range: southern New York (Long Island and Staten Island) south to the 
Carolinas and west to Ohio. In North Carolina the insect occurs at in- 
land stations. Along the coast it is replaced by the subspecies seminole. 



4. TRACHYMYEMEX SEPTENTRIONALIS OBSCURIOR (Wheeler) 

Atta (T.) septentrionalis subsp. obscurior Wheeler, Bull. Amer. Mus. Nat. 

Hist., Vol. 23, p. 709 (1907) 9 ; Wheeler, Jour. N. Y. Ent. Soc., Vol. 19, 

p. 246(1911) 9 9. 
A. (T.) septentrionalis subsp. obscurior var. crystalline. Wheeler, Ibid., Vol. 19, 

p. 247 (1911) 9 9 d". 
A. (T.) septentrionalis subsp. obscurior var. irrorata Wheeler, Ibid., Vol. 19, 

p. 247 (1911) 9. 

Type loc: Austin, Texas (by Wheeler's 1911 designation). Types: M.C.Z. 
Range: central Texas and Louisiana and northward through the Mississippi 

Valley. 



5. TKACHYMYRMEX SEPTENTRIONALIS SEMINOLE (Wheeler) 

Atta (T.) septentrionalis subsp. obscurior var. seminole Wheeler, Jour. N. Y. 
Ent. Soc., Vol. 19, p. 247 (1911) 9 9 cf. 

T. septentrionalis subsp. obscurior var. seminole M. R. Smith, Amer. Mid. 
Naturalist, Vol. 37, No. 3, p. 590, pi. 16, fig. 59 (1947) 9 . 

Type loc: Miami, Florida. Types: M.C.Z., Coll. W. S. Creighton. 

Range: Florida and the eastern Gulf States and northward along the At- 
lantic Seaboard to the Carolinas. 



6. THACHYMYRMEX TURRIFEX (Wheeler) 

Atta (T.) turrifex Wheeler, Psyche, Vol. 10, p. 100, fig. 6a (1903) 9 ; Wheeler, 

Bull. Amer. Mus. Nat. Hist., Vol. 23, p! 709, pi. 49/fig. 3 (1907) 9 . 
Type loc: Austin, Texas (by present designation). Types: M.C.Z. 
Range: central and western Texas. 



7. TRACHYMYRMEX TURRIFEX CAROLI (Wheeler) 

Atta (T.) turrifex subsp. caroli Wheeler, Jour. N. Y. Ent. Soc., Vol. 19, p. 248 

(1911) 9. 

Type loc: Huntsville, Texas. Types: lost? (see below). 
Range: known only from type material. 



CREIGHTON: ANTS OF NORTH AMERICA 325 

The writer has been unable to discover any types of caroli in the 
M.C.Z. and A.M.N.H. collections. Since the subspecies was based 
on only two worker types, it is possible that these have been mis- 
placed and are still in existence. It seems very doubtful that caroli 
is a valid race but, until the types are rediscovered and additional ma- 
terial secured, there is little that can be done with this insect. 



Genus ACROMYRMEX Mayr 

Subgenus MOELLERIUS Forel 

In both structure and habits the ants of the genus Acromyrmex 
show a close relationship to the genus Atta. The best structural cri- 
terion for the separation of the two groups appears to be the character 
of the radial cell in the winged castes. Emery states that this cell in 
Acromyrmex is never more than four times as long as broad, while in 
Atta it is at least six times as long as broad. This distinction appears 
to be exceptionally clear in all the species which the writer has been 
able to examine. But no such clarity exists in the case of the differences 
which are supposed to distinguish the workers of the two genera. In 
the genus Atta the worker possesses only two pairs of dorsal spines on 
the promesonotum. In Acromyrmex there are supposed to be at least 
three pairs of dorsal spines in that area. In most cases this is true, but 
there are a number of species of Acromyrmex in which the anterior 
pair of dorsal pronotal spines are reduced in size and in the case of the 
species landolti they are replaced by angular ridges which are not 
spine-like at all. The sexual phases of landolti seem to be unknown, 
hence it is impossible to say whether they are also transitional. But 
certainly on the basis of pronotal armature the worker of landolti 
might be placed in the genus Atta with perfect propriety. This diffi- 
culty gives little trouble to the student of North American ants, 
for our single species, Acromyrmex (Moellerius) versicolor, has three 
distinct pairs of pronotal spines and so differs sharply from Atta 
texana, where there are only two pairs present. 

There are significant habit differences which distinguish these two 
insects in the field. The nests of Acromyrmex versicolor, while similar 
to those of Atta texana, are of notably smaller average size. The 
nests of versicolor possess fewer craters and a smaller number of cham- 
bers for the fungus gardens. These chambers are often constructed in 
coarse, rather gravelly soil near the surface of the ground. In texana 
the passages leading down to the chambers are single, in versicolor 
they are usually branched. Wheeler was of the opinion that versi- 



ozo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

color and its subspecies chisosensis are both much more xerophilous 
than texana. There can be no doubt that this view is correct in the 
case of the typical versicolor, which prefers nest sites of exceptional 
aridity. But I doubt that this is also true of the subspecies chisosensis. 
It may be recalled that Wheeler was never able to discover a colony of 
this insect in the field. The type specimens were dead workers taken 
from a spider web and the location of the single nest, later found by 
Williams, led Wheeler to suppose that chisosensis inhabits the very 
arid canyons on the southern slopes of the Chisos Mountains. When 
the writer visited this region in 1933 there had been an almost un- 
broken drought for the previous twenty-two months. The canyons 
on the southern slopes were incredibly dry and barren. But on the 
northern slopes the situation was somewhat better and there, in a tim- 
bered area at considerable elevation, two nests of chisosensis were dis- 
covered. From this very limited data I would incline to the view that 
chisosensis is less xerophilous than the typical versicolor. We need 
more data before any certain conclusion can be reached about the 
nest site preference of this interesting ant. 

Key 1o the subspecies of Acromyrmex (Moellerius) versicolor Pergande 

Cephalic sculpture heavy and dense, the surface opaque; color deep, reddish 

brown versicolor 

Cephalic sculpture not dense enough to produce a completely opaque surface; 
color yellow versicolor subsp. chisosensis 



1. ACROMYRMEX (MOELLERIUS) VERSICOLOR (Pergande) 

Alia versicolor Pergande, Proc. Calif. Acad. Sci. (2), Vol. 4, p. 31 (1893) 9 . 
Acromyrmex (M.) versicolor Emery in Wytsman, Genera Insectorum, Fasc. 

174, p. 351 (1922). 
Alia (M.) versicolor Emery, Mem. Soc. Accad. Bologna (6), Vol. 2, p. 108 

(1905) 9 ; Wheeler, Bull. Amer. Mus. Nat. Hist,, Vol. 23, p. 703, pi. 49, 

fig. 5 (1907) 9 9 c?; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 586, pi. 15, fig. 57 (1947) 9 . 

Type loc: Calamujuit, Lower California. Types: U.S.N.M. 
Range: deserts of southern Arizona and southeastern California south into 

Mexico. 

2. ACROMYRMEX (MOELLERIUS) VERSICOLOR CHISOSENSIS (Wheeler) 

Atta (M.) versicolor subsp. chisosensis Wheeler, Bull. Amer. Mus. Nat. Hist., 

Vol. 23, p. 705 (1907) 9 . 
Acromyrmex (M.) versicolor subsp. chisosensis Emery, in Wytsman Genera 

Insectorum, Fasc. 174, p. 351 (1922). 



CREIGHTON: ANTS or NORTH AMERICA 66 

Type loc: Chisos Mountains, Texas. Types: A.M.N.H., M.C.Z. 

Range: mountains of the Big Bend area in Texas. Although there are no 

records of this insect from Mexico it probably occurs in the Provinces of 

Chihuahua and Coahuila. 

In his original description of chisosensis Wheeler used the reduced 
number of gastric tubercles as a distinguishing characteristic. I have 
found this distinction difficult to apply because the number of tu- 
bercles varies with the size of the worker. In the smaller workers of 
the typical versicolor the number of gastric tubercles is often greatly 
reduced. Hence, if this distinction is used, it must be remembered 
that it will hold only in the case of the largest workers. 



Genus ATTA Fabricius 
(Plate 42, figures 1-5) 

In 1942 Goncalves published a monograph of the genus Atta in 
which he proposed to divide the group into three subgenera. His 
three subgenera, which correspond exactly to the three groups of 
species set up by Emery in the Genera Insectorum, are based primarily 
on the characteristics of the genitalia of the male but Goncalves was 
also able to draw distinctions from the worker caste which were based 
on the character of the thoracic spiracles and the occipital spines. I 
think it may be doubted that myrmecologists will accept Goncalves 
proposal, for it seems that what he has described are specific differ- 
ences rather than subgeneric ones. It is true that each of his sub- 
genera contains at least two species but it has long been recognized 
that some of these species are very closely related. His subgenus 
Archeatta, for example, contains the species mexicana, texana and 
insularis, a group of forms which some authorities have regarded as 
components of a single species. On this basis, it is perfectly correct 
to regard the characteristics on which the subgenus Archeatta was 
erected as being the specific characteristics of the insularis complex. 
I believe that Senhor Goncalves has overlooked the fact that the at- 
tine genera are more closely related than those of any other myrmi- 
cine tribe. There is scarcely a genus in this group which does not 
possess one or more species whose structure clearly indicates a rela- 
tionship with the members of another genus. In the past this inter- 
gradation has been the cause of considerable confusion, since it gave 
rise to widely different proposals for the treatment of genera and sub- 
genera in the Attini. The difficulty has been solved by the more or 
less tacit agreement to recognize genera among the Attini even when 
they are known to intergrade. Thus Acromyrmex, which is connected 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



to Atta through the species landolti, and Trachymyrmex, which grades 
into Cyphomyrmex through the transitional Mycetosoritis and into 
Atta through such species as jamaicensis, etc., have both been ac- 
corded generic status. If this is inconsistent with the practice found in 
other myrmicine tribes, it is at least expedient. For if one starts re- 
ducing these intergrading groups to subgenera, the logical outcome is 
a single genus, Atta, in which most of the present attine genera appear 
as subgenera. Something much like this occurred when Emery tried 
to expand Cyphomyrmex to include a number of closely related groups. 
But since the relationship of most attine genera to each other is al- 
ready very similar to that which exists in the case of subgenera in 
other tribes, it follows that further subgeneric division within the 
Attini can only be justified for very compelling reasons. I do not re- 
gard the evidence on which Senhor Gonfalves bases his subgenera as 
of this character, hence I have treated the genus Atta as a single unit 
in this work. 

As far as is known at present, only one member of the genus Atta, 
A. texana, occurs north of the Mexican border. The habits of this in- 
sect have been repeatedly, although often erroneously publicized. It 
has been studied by Buckley (1860), Lincecum (1867), Townsend 
(1870), McCook (1879) and Wheeler. The following account is largely 
taken from the excellent treatise which the latter author published 
in 1907. The nests of texana are constructed by preference in the vi- 
cinity of tree-bordered streams. The mature colony is very large and 
the nest may be of striking proportions. Above ground it consists of 
a series of shallow craters about fifteen inches in diameter and five or 
six inches high. These may be so closely packed together that they 
fuse to form an irregular mass of soil. The total area covered by the 
craters may be a hundred square feet or more. At the bottom of each 
crater is a single, irregular opening which leads through an unbranched 
passage to one of the nest chambers. These are usually built in a 
layer of sand. To reach such a sandy layer, the ants will sometimes 
drive the passages through twelve or fifteen feet of overlying soil. 
The chambers themselves vary considerably in size. They may, at 
times, be as much as three feet long and McCook ('79) reported one 
very large nest chamber which he claimed was the size of a flour- 
barrel. As a rule, however, the size of the chambers averages less. 
They are usually about one foot in length and less than a foot high. 
It is in these chambers that the fungus garden is prepared and the 
fungus grown. The substrate on which the fungus is cultivated con- 
sists of triturated leaves and other bits of vegetable material. In the 
larger chambers the garden is arranged in the form of a loose, floccu- 
lent mass which lies on the floor. In the smaller chambers the garden 
is frequently suspended on rootlets which dangle from the roof. In 



CREIGHTON: ANTS OF NORTH AMERICA 6zy 

either case it soon becomes covered with a dense mass of mycelial 
filaments. On this mycelium are produced globular swellings which 
Wheeler has called bromatia.. These and the filaments themselves 
constitute the food of the leaf-cutters. The arrangement of the fungus 
garden and its subsequent care after the mycelium has become es- 
tablished is mainly the work of the smallest caste of workers. They 
not only tend the fungus garden but also look after the larvae, which 
are usually placed in the interstices of the garden where they are sur- 
rounded by the mycelial filaments on which they feed. The cutting 
and transportation of the leaf fragments is primarily accomplished by 
the media workers, although minor workers sometimes engage in this 
phase of activity. After the leaf fragments have been brought into the 
nest they are softened by chewing and the addition of salivary juices. 
When sufficiently macerated they are built into the garden. The major 
workers appear to take very little part in the fungus growing. Indeed, 
their presence in the fungus garden seems to be detrimental, since 
their large size and weight breaks down the delicate substrate. The 
majors function in the defence of the colony and as a rule do not appear 
on the surface unless the nest is disturbed. Wheeler has shown that 
texana is very sensitive to changes in temperature and humidity. 
Their daytime foraging is confined to the cooler months and with the 
onset of hot summer weather they remain in the nest until dark. He 
has also pointed out that the size of the ventilating passages is care- 
fully regulated to insure the proper humidity for the fungus gardens. 
In very dry weather the apertures may be entirely closed. 



1. ATTA TEXANA (Buckley) 

Myrmica texana Buckley, Proc. Acad. Nat. Sci. Phila., p. 233 (1860) 9 9 cf . 

Atta texana Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 23, p. 700, pi. 49, 
figs. 11-14 (1907) 9 9 d"; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 
No. 3, p. 591, pi. 15, fig. 58 (1947) 9 . 

Oecodoma texana Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 374 (1867) 9 9 cf. 

Attafervens Townsend, Ann. Ent. & Bot., Vol. 2, p. 224, figs. 202, 203 (1870) 
9 9. 

Type loc: Texas. Types: none known to exist. 

Range: the range of texana is largely confined to south central Texas. A line 
drawn from Houston through Austin and San Antonio and thence south 
to Brownsville would include the majority of the records. This insect 
undoubtedly occurs in northeastern Mexico, although there is too little 
data at present to determine the southern limit of the range. It seems, 
however, that unlike several other species which range northward from 
Mexico and into the eastern Gulf states, texana does not occur east of 
Texas, although there are areas in Louisiana and Mississippi which ap- 
pear suitable for it. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Subfamily DOLICHODERINAE 

The representatives of the Subfamily Dolichoderinae which live in 
America north of Mexico are a rather uniform group both in habits 
and structure. All six of the genera which occur within our borders 
exhibit a very generalized type of behavior. They prefer to nest in 
soil but will utilize other nest sites on occasion. They show little evi- 
dence of dietary specialization, for all will feed on honey-dew or other 
insects or practically any food that is readily available. This latter 
characteristic has made some of the species serious pests, for they will 
often invade homes in search of food. It is interesting to note that 
while one genus, Dorymyrmex, is rather notably xerophilous, it has 
retained the same generalized feeding habits that mark the rest of the 
group. 

The structure of several of the genera is disconcertingly similar. 
It seems impossible to secure clear-cut external characters to separate 
Iridomyrmex, Forelius and Tapinoma. In these genera, as elsewhere 
in the subfamily, the best generic criteria are internal. The structure 
of the gizzard can be used to supplement the rather unsatisfactory ex- 
ternal differences but, since the examination of this organ involves 
microtechniques which are scarcely feasible in the field, no attempt 
has been made to give these internal distinctions here. A full exposi- 
tion of them may be found in the key which Emery published in the 
Genera Insectorum in 1912 (Fasc. 137). It should be noted that several 
of the distinctions employed in the generic key below are applicable 
only to our species and will not apply to the genus as a whole. Where 
there is so much difficulty in arriving at satisfactory generic distinc- 
tions it seems best to make certainty of recognition the primary con- 
sideration. 

Key to the Genera in the Subfamily Dolichoderinae 

1. Declivious face of the epinotum very strongly concave; integument stiff 
and brittle; epinotum and often much of the remainder of the thorax, 

heavily sculptured Dolichoderus 

Declivious face of the epinotum straight or nearly so; integument thin and 
flexible; sculpture everywhere fine ! 

2. The epinotum with a prominent, sharp, tooth-like protuberance projecting 
vertically at the junction of the basal and declivious faces; third segment 
of the maxillary palp very long, as long or longer than the three succeeding 

segments taken together . ' Dorymyrmex 

The junction between the basal and declivious faces of the epinotum 
unarmed, rounded or angular; third segment of the maxillary palp not 
unusually long and notably shorter than the three succeeding segments 
taken together , 3 



CREIGHTON: ANTS OF NORTH AMERICA 661 

3. Dorsum of the thorax without an impression at the mesoepinotal suture; 
worker caste moderately polymorphic; female 10 mm. or more in length 

Liometopum 

Dorsum of the thorax at least with a slight impression at the mesoepinotal 
suture; worker caste monomorphic; female 6 mm. or less in length 4 

4. Scale of the petiole vestigial Tapinoma 

Scale of the petiole present although often small and difficult to see .... 5 

5. Erect body hairs long and sparse, absent on the scapes and tibia; scale of 
the petiole long enough for the tip to project beyond the overhanging 

anterior face of the gaster Iridomyrmex 

Erect body hairs short and numerous, present on scapes and tibiae; scale 
of the petiole small, short and largely concealed by the overhanging anterior 
face of the gaster Forelius 



Genus DOLICHODERUS Lund 



Subgenus HYPOCLINEA Mayr 
(Plate 43, figures 1-4) 

The representatives of Dolichoderus which occur in the United 
States and Canada all belong to the subgenus Hypoclinea, a group 
which occurs in the north temperate portion of both hemispheres. 
Although Hypoclinea was monographed by Mayr in 1866 and by 
Wheeler in 1905, there are still points in the taxonomy of our species 
which are not satisfactory. The writer finds himself at odds with so 
many of the statements that Wheeler made in 1905 that it seems worth 
while to review the opinions which he advanced at that time. WTieeler 
constructed a phylogenetic tree for our representatives of Hypoclinea 
by using sculpture as the indicator of evolutionary advance. Accord- 
ing to this view the ancestral form of Hypoclinea was a heavily 
sculptured insect, hence the weaker the sculpture the more advanced 
its possessor was supposed to be. On this basis plagiatus became the 
prototype from which our other species have been derived. WTieeler's 
view that the species are closely related agreed with Mayr's earlier 
pronouncement. But WTieeler was unwilling to accept Mayr's ob- 
servation that the species are not interconnected. Wheeler's phylo- 
genetic plan demanded interrelationships and he attempted to supply 
them. He made pustulatus a subspecies of plagiatus and treated both 
pustulatus and the subspecies davisi as intermediate conditions be- 
tween mariae and some ancestral form similar to plagiatus. Some 
years later Wheeler took a similar view of the variety blatchleyi. 
There is no objection to phylogenetic speculation but it is not un- 



332 BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

reasonable to ask that it subserve facts and not supersede them. It 
is my opinion that Wheeler overestimated the importance of his 
phyletic scheme and allowed it to exercise an unjustifiable effect on 
his taxonomy. It is easy to demonstrate that pustulatus cannot be 
considered a subspecies of plagiatus on any grounds. It can be shown 
that neither davisi nor blatchleyi are transitional between the species 
which they are supposed to link. It is plain that Wheeler minimized 
the specific differences which mark the representatives of Hypoclinea 
and strove to give the impression that it is an intergrading group. 
The writer agrees with Mayr that it is not, and can see nothing to be 
gained by forcing the species into a phyletic system to which they seem 
very ill-adapted. I further see no justification for Wheeler's recogni- 
tion of the color phases which he set up as varieties. It may be noted 
that in every case the variant or the 'typical' form with which it was 
compared was represented by inadequate material. Thus gagates (or, 
as it was later called, aterrima) was established because of a wholly 
inconsequential color difference which supposedly distinguished it 
from the one specimen in WTieeler's collection which he regarded as 
the 'typical' taschenbergi. The subspecies davisi was described from 
seven specimens, inornatus and blatchleyi from eight each and beuten- 
muelleri from eleven, all strays. None of these variants give the 
slightest indication that they possess any distinguishing distributional 
features and most of them are so inconstant that the definitive dis- 
tinctions apply well only in the case of selected individuals. For the 
above reasons I have treated all of Wheeler's variants as synonyms 
of their respective species. 

Wheeler's observations on the habits of these insects are far more 
satisfactory. He was able to show that both marine and taschenbergi 
prefer to nest in pure sand. The nests are usually constructed be- 
neath tufts of grass or small bushes and consist of a single, large cham- 
ber a foot or more deep and several inches across. The roots of the 
plant ramify through this chamber and serve not only to keep its 
walls from collapsing but also as a sort of a scaffolding on which the 
brood is placed. In some nests the plant is partially buried by a low 
mound of collected detritus but there seems to be no fixity in this 
habit for as often as not the nest is unthatched. Both mariae and 
taschenbergi produce large colonies consisting of thousands of indi- 
viduals. Both species forage in files and are active in collecting the 
sugary secretions of coccids and aphids. They will also eat other in- 
sects. Wheeler's account has been repeatedly confirmed by subse- 
quent observers. The colonies of pustulatus and plagiatus are notably 
smaller than those of the two preceding species. The nests of pus- 
tulatus have been described by the Wessons (1940) as consisting of a 



CREIGHTON: ANTS OF NORTH AMERICA 666 

hard, thin, firm carton shell built above ground and about the blades 
of a tuft of grass. The entrance of the nest consists of a small carton 
tube about three-quarters of an inch long which projects from the 
main shell 'like a spout on a tea kettle'. The Wessons described other 
nests of plagiatus which seem to be nothing more than irregular cham- 
bers under piles of detritus. It may be assumed that such nests are 
temporary shelters for all the species of Hypoclinea are prone to move 
to new nest sites. There is little agreement concerning the nests of 
plagiatus. Wheeler (1905) and Cole (1940) have both taken plagiatus 
from small, obscure nests in the soil. These seem to consist of little 
more than a few short passages leading away from the single nest en- 
trance. The Wessons have taken nests of plagiatus in hollow stems 
and in curled up leaves. 

All of our species of Hypoclinea possess repugnatorial glands which 
produce a volatile secretion with an odor which has been described as 
'smoky or pungent'. In this respect they differ from our other dolicho- 
derine genera in which the odor produced is generally like that of 
butyric acid. 



Key to the species of Hypoclinea 

1. Cephalic foveolae coarse, deep and very close-set so that the surface between 
them forms a reticulo-rugose pattern; the antennal scapes with numerous 

short, erect hairs on their anterior surfaces plagiatus 

Cephalic foveolae shallow, often replaced on the front and vertex by small 
punctures, the foveolae well separated with the surface between them deli- 
cately shagreened and never forming a reticulo-rugose pattern; antennal 
scapes usually without erect hairs, rarely one or two present 2 

2. Epinotum, seen from above, subquadrate, very slightly or not at all longer 

than broad; color uniform brownish black or piceous taschenbergi 

Epinotum, seen from above, very distinctly longer than broad; color rarely 
as above, often bicolored or at least with the thorax lighter than the 
gaster 3 

3. Dorsum of the epinotum and mesonotum with coarse, deep, close-set 
foveolae forming a reticulo-rugose pattern; the mesopleurae very smooth 

and shining pustulatus 

Dorsum of the epinotum and mesonotum granulose or densely shagreened; 
foveolae, when present, shallow and obscure; the mesopleurae in large part 
or entirely shagreened, subopaque or dull mariae 



1. DOLICHODEBUS (HYPOCLINEA) MARIAE Forel 

D. mariae Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 20, p. 349 (1884) 9 ; Mayr, 
Verh. Zool-bot. Ges. Wien, Vol. 36, p. 436 (1886) 9 9 ; Wheeler, Bull. 
Amer. Mus. Nat. Hist., Vol. 21, p. 306, fig. A (1905) 9 9 <?. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



D. mariae subsp. davisi Wheeler, Ibid., p. 308 (1905) 9 . 
D. mariae var. blatchleyi Wheeler, Proc. Ind. Acad. Sci., Vol. 37, p. 462 (1917) 9 
Type loc: Vineland, New Jersey. Types: none in this country. 
Range: southern New England south to the Gulf States and west as far as 
Illinois and Oklahoma. The insect is very sporadic over its entire range. 

The variety blatchleyi appears to be no more than a very minor 
color variation of mariae and the writer can see no basis whatever for 
Wheeler's statement that it is transitional between mariae and pus- 
tulatus. The thoracic sculpture of mariae is wholly different from that 
of pustulatus (see key) and in addition the scapes of mariae are dis- 
tinctly longer than those of pustulatus. Wheeler's variety blatchleyi 
agrees in both respects with mariae. It is 'transitional' to pustulatus 
only insofar as its color is a trifle darker than that usually encountered 
in specimens of mariae. In my opinion blatchleyi is an insignificant 
color phase of mariae which should never have been named. The 
subspecies davisi is scarcely more distinct, although there are cir- 
cumstances which necessitate a more careful consideration of thisform. 
From Wheeler's description of davisi it would appear that the insect 
is notably different from the typical mariae. Indeed, if these differ- 
ences were as described, it would be possible to regard davisi as a 
separate species. Unfortunately, this is not the case. There is no 
significant difference in the size of the two insects, for the workers of 
davisi are fully as large as the small workers of mariae and since davisi 
is known from very limited material, the absence of larger workers is 
no proof that they do not exist. The structure of the epinotum and 
the petiolar scale in davisi is not different from that of mariae and the 
distinctions noted by Wheeler in 1905 appear to be contrary to fact. 
Nor is davisi distinguished by a unique hair pattern. Since Wheeler 
considered the typical mariae as being devoid of erect hairs on the 
upper surface of the body, he was able to use the presence of erect 
hairs in davisi as a distinguishing feature. The typical mariae is not 
devoid of erect hairs on the upper surface of the body. There are 
usually a few erect hairs present on the front and vertex in mariae 
and occasionally one or two on the pronotum as well. It may be ad- 
mitted that the erect hairs in davisi are a little more abundant than is 
usually the case with mariae but the difference is by no means as great 
as would be inferred from Wheeler's description. We have in davisi 
an insect in which the color is a little duller, the cephalic sculpture a 
trifle heavier and the erect hairs slightly more numerous than is or- 
dinarily the case with mariae. Even though these differences are less 
striking than Wheeler supposed, it might be possible to retain davisi 
as a subspecies if it had any distinguishing peculiarity of range. Un- 
fortunately, it does not. So far, all the material of davisi has come 



CREIGHTON: ANTS OF NORTH AMERICA 66i) 

from the New Jersey pine barrens. There it occurs with marine for, 
although the latter insect has a much more extensive range, it is 
abundant only in the pine barren regions. Since davisi is clearly not 
a geographical race of mariae and since the differences which it shows 
are certainly not of sufficient magnitude to justify specific status, it 
has been treated as a synonym of mariae in the present work. It may 
be added that davisi has the long antennal scapes and the character- 
istic thoracic sculpture of mariae and has nothing in common with 
plagiatus or pustulatus. I can see no reason why Wheeler should have 
regarded davisi as a 'hybrid form' which combined the characters of 
mariae and plagiatus. 

2. DOLICHODERUS (HYPOCLINEA) PLAGIATUS (Mayr) 

Hypoclinea plagiatus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 960 (1870) 9 . 
D. plagiatus Mayr, Ibid., Vol. 36, p. 436 (1886) 9 9 ; Wheeler, Bull. Amer. 

Mus. Nat. Hist., Vol. 21, p. 310, fig. c (1905) 9 9 cf 1 . 
D. borealis Provancher, Natur. Canad., Vol. 5, p. 408 (1888) 9 . 
D. plagiatus var. inornatus Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, 

p. 313 (1905) 9 . 

Typeloe: Illinois. Types: none in this country. 
Range: southern Ontario and New Brunswick south to Georgia and Tennessee 

and west to North Dakota. Most of the southern records for plagiatus 

come from stations in the Appalachian Highlands. 

The color variety which Wheeler described as inornatus is not of 
sufficient constancy to justify recognition. Both the thorax and the 
gaster of plagiatus vary considerably in the extent of their infuscation, 
hence it is usually possible to find specimens referable to inornatus in 
any long nest series of the typical form. 



3. DOLICHODERUS (HYPOCLINEA) PUSTULATUS Mayr 

D. pmtulatus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 436 (1886) 9 9 . 

D. plagiatus subsp. pustulatus Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, 
p. 313 (1905) 9 9 . 

D. plagiatus var. beutenmuelleri Wheeler, Ibid., Vol. 20, p. 304 (1904) 9 ; 
Wheeler, Ibid., Vol. 21, p. 313 (1905) 9 . 

Typeloe: New Jersey (by present restriction). Types: none in this country. 

Range: southern Nova Scotia south to Florida and southwestward to Texas. 
In the northern United States the western limit of the range appears to 
lie in Illinois but in the south it extends considerably further west. Dr. 
Smith has recorded pustulatus from Norman, Oklahoma and I have speci- 
mens taken by Dr. P. J. Darlington in Brownsville, Texas. 



33b BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Wheeler's variety beutenmuelleri is quite indefensible. As Mayr 
noted in his original description of pustulalus, the gastric spotting of 
this species is very variable. This is also true of the coloration of the 
thorax which is sometimes just as dark as the head and gaster. As has 
been noted on an earlier page, it is impossible to treat pustulatus as a 
subspecies of plagiatus. The writer finds it impossible to follow 
Wheeler's reasoning in this matter. He was certainly aware of the 
notable difference in the sculpture of the two insects, for he used this 
difference as the first split in his key. But despite the fact that the 
sculpture of pustulatus indicated a closer relationship with mariae 
and taschenbergi than with plagiatus, Wheeler allied it to the latter 
form. It is difficult to avoid the impression that the main reason why 
he did so was to provide a connection with his hypothetical 'plagiatus- 
like ancestor'. The sculpture of pustulatus lacks entirely the reticulo- 
rugose character which marks plagiatus, except on the epinotum and 
to a lesser extent on the mesonotum. The head and pronotum are 
covered with shallow, rather widely spaced foveolae between which 
the surface is smooth with only a delicate shagreened sculpture pres- 
ent. The promesonotum is more strongly convex in pustulatus, with 
the promesonotal suture very much more distinct. Erect hairs are 
rarely met with on the scapes of pustulatus, while they are regularly 
present in considerable abundance on the scapes of plagiatus. Finally, 
since the ranges of the two species are largely coincidental over most 
of the eastern United States, it would be out of the question to con- 
sider pustulatus as a subspecies from a distributional standpoint if 
for no other reason. 



4. DOLICHODERUS (HYPOCLINEA) TASCHENBERGI (Mayr) 

Hypodinea taschenbergi Mayr, Sitz. Akad..Wiss. Wien, Vol. 53, p. 498 (1866) 9 ; 

Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 958 (1870). 
D. taschenbergi Mayr, Ibid., Vol. 36, p. 436 (1886) 9 ; Wheeler, Bull. Amer. 

Mus. Nat. Hist., Vol. 21, p. 309, fig. B (1905) 9 ; M. R. Smith, Amer. 

Mid. Naturalist, Vol. 37, No. 3, p. 590, pi. 16, fig. 60 (1947) 9 . 
D. taschenbergi var. gagates Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, 

p. 310 (1905) 9 (nee Emery). 

D. taschenbergi var. aterrima Wheeler, Ibid., Vol. 34, p. 417 (1915) (nomen new.). 
Type loo: North America. Types: none in this country. 
The original description of taschenbergi did not cite Louisiana as the type 

locality although the types may have been taken there. 
Range: Nova Scotia west to Manitoba and south to the Gulf States. The 

insect appears to be rare in the southern half of its range. 

The characters on which Wheeler based the variety gagates (= ater- 
rima) are so little different from those described for the typical form 



CEEIGHTON: ANTS OF NORTH AMERICA 66 1 

that it does not seem to represent even a color phase and one wonders 
why Wheeler felt it necessary to give a name to what is so clearly a 
synonym of taschenbergi. 



Genus LlOMETOPTJM Mayr 
(Plate 44, figures 1-4) 

With the recognition of the specific status of occidentale by Wheeler 
in 1917 this insect was given a taxonomic stability which it had con- 
spicuously lacked during the previous quarter of a century. It would 
seem, however, that Wheeler was at that time still unaware of the 
specific characteristics of the worker of occidentale. For Wheeler never 
realized that luctuosum is much more closely related to occidentale 
than to apiculatum. As long as luctuosum is to be considered as a sub- 
species it must be assigned to occidentale, not only because of its 
closely related structure but also because its distribution indicates 
that it cannot be considered a geographical race of apiculatum. This 
point has been explained in more detail on a subsequent page. It 
seems well to mention here certain taxonomic difficulties which have 
to do with apiculatum. 

Wheeler's 1905 description of that species was a composite one. It 
was based upon a female from Mexico which Mayr had sent him, a 
female and a male from Arizona and a series of workers taken on the 
volcano of Colima in southern Mexico. It follows, therefore, that of 
the three castes described only the female can be said to be based 
upon authentic material. I mention this matter because certain fea- 
tures embodied in Wheeler's figures and descriptions accord very 
poorly with most of the material which he assigned to apiculatum. 
The petiolar scale of the worker was figured and described as having 
a long, slender spine arising from the middle of the crest. The petiolar 
scale of the female was shown as distinctly lyrate with the central 
notch bounded at either side by a tooth-like projection which angles 
outward from the notch. I do not contend that such conditions never 
occur in specimens coming from the United States but I have -never 
encountered them. In the material from the western states the crest 
of the petiole in the worker is produced upward in a sharp angle but 
this angle is not surmounted by a spine. The scale of the female has 
a strong notch in the middle of the crest but it is certainly not lyrate 
and the crest at either side of the notch is stout, not tooth-like and 
not turned outward. This leads one to suspect that the specimens of 
apiculatum coming from the United States are subspecifically different 
from those which occur in southern Mexico. But since we know that 



doo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

specimens of apiculatum from northern Mexico are like those from the 
western states and since there is no way of proving exactly what the 
worker of Mayr's apiculatum is like without recourse to type speci- 
mens, it seems best to leave matters as they are until this difficulty 
can be resolved by a further examination of type material. 

The ants belonging to Liometopum are more aggressive than those 
of most of our dolichoderine genera. Both apiculatum and occidentale 
often form large colonies and are very pugnacious insects. They 
forage in files and attack fiercely if they are disturbed. They possess 
a secretion with a powerful and disagreeable odor like that of butyric 
acid and they spray this on intruders. The nests are usually built 
under stones or in hollow trees. The nest chambers are sometimes 
subdivided by a ramifying mass of paper-like material. The insects 
manufacture this by mixing bits of soil and vegetable detritus with a 
secretion which hardens and gives solidity to the mass. Wheeler has 
shown (1905) that our species of Liometopum will tend aphids and 
coccids. The European species microcephalum is said to eat aphids 
but not to use their secretions. Our species will feed upon any insects 
they can capture. In Emery's opinion the females of Liometopum are 
losing the power of flight (1891). Those of apiculatum at least, are 
certainly exceptionally gross and clumsy insects. Our three forms 
can be separated as follows : 



Key to the species of Liometopum 

1 . The antennal scapes of the largest workers surpassing the occipital corners 
by an amount at least twice as great as the maximum thickness of the 
scape; the anterior edge of the mesonotum not raised above the adjacent 
edge of the pronotum; erect hairs on the gastric dorsum very uneven in 
length with at least some of them about as long as those on the pronotum 

apiculatum 

The antennal scapes of the largest workers surpassing the occipital corners 
by an amount which does not exceed the maximum thickness of the scape ; 
the anterior edge of the mesonotum distinctly raised above the adjacent 
edge of the pronotum; erect hairs on the gastric dorsum, when present, 
short and of approximately equal length f 

2. Erect hairs on the dorsum of the gaster abundant, those on the thorax 
present over most of the upper surface; the body only moderately shining; 

thorax in part or entirely yellow occidentale 

Erect hairs on the dorsum of the gaster very sparse or absent, those on the 
thorax largely confined to the pronotum; the body rather strongly shining; 
color always uniform brown occidentale subsp. luctuvsum 



CREIGHTON: ANTS OF NORTH AMERICA ooy 

1. LIOMETOPUM APICULATUM Mayr 

L. apiculatum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 961(1870) 9 ; 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 331 (1895) 9 ; Viereck, Trans. Amer, 

Ent. Soe., Vol. 29, p. 71 (1903) 9 ; Wheeler, Bull. Amer. Mus. Nat, Hist., 

Vol. 21, p. 322, fig. a-c (1905) 9 9 cf . 
Type loc: Mexico. Types: none in this country. 
Range: Colorado through New Mexico, Arizona and western Texas into 

Mexico. 

This species generally nests in foot-hill areas at elevations between 
5000 and 7000 feet. Wheeler was of the opinion that it is always asso- 
ciated with live-oak trees and in general this seems to be true. But 
in the northern part of its range it sometimes occurs in stations where 
no live oak trees are present. It seems worth noting that the female 
of apiculatum, labelled as a type in the collection of the M.C.Z., is 
the specimen which Mayr sent to Wheeler. It is not a type, since the 
type female of apiculatum was first described by Emery. 



2. LIOMETOPUM OCCIDENTALE Emery 

L. microcephalum var. occidentale Emery, Zool. Jahrb. Syst., Vol. 8, p. 330 

(1895) 9 cf . 
L. apiculatum var. occidentale Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, 

p. 324 (1905) 9 . 
L. occidentale Wheeler, Proc. Amer. Acad. Arts Sci. Boston, Vol. 52, No. 8, 

p. 522 (1917) 9 cf; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 590, pi. 16, fig. 61 (1947) 9 . 
Type loc: San Jacinto, California. Types: none in this country. A part of 

the type series is present in the M.C.Z. 
Range: northern Oregon through California into Mexico. 

This species nests at lower elevations than does its subspecies 
luctuosum. In California it appears to be most abundant at levels 
between 1000 and 4000 feet and is only rarely taken at higher eleva- 
tions. 



3. LIOMETOPUM OCCIDENTALE LUCTUOSUM Wheeler 

L. apiculatum subsp. luctuosum Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, 
p. 325 (1905) 9 . 

Type loc: Cheyenne Canyon, Colorado Springs, Colorado. Types: M.C.Z. 

Range: southern Wyoming to New Mexico and Arizona and the mountains 
of California. The insect appears to be rare in Utah and Nevada although 
one would expect it to be abundant in the mountains of these states. 



64>J BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

The short antennal scapes and the elevated mesonotum of luctuosum 
relate it to occidentale rather than to apiculatum. The erect hairs on 
the gaster, when present, are also like those of occidentale. It is of in- 
terest to note in this connection that while the preference of luctuosum 
for nests at higher levels (4000-7000 feet) keeps its range largely sep- 
arate from that of occidentale, the insect occurs in the same stations as 
apiculatum at the eastern end of its range. For this reason alone it 
would be impossible to consider luctuosum as a subspecies of apicu- 
latum. 



Genus IRIDOMYRMEX Mayr 
(Plate 45, figures 1-4) 

Some of the species belonging to this genus present a problem to 
anyone dealing with our native ant fauna for there seems to be no al- 
together satisfactory method for handling several of the imported 
forms. There is no question, of course, in the case of the notorious 
Argentine ant, /. humilis. Most people living on the Gulf Coast or 
in southern California can testify that this insect has completely 
adapted itself to life in the United States and will have to be regarded 
as a permanent, if unpleasant, addition to our ant fauna. This is not 
so clear for other imported species which have turned up in green- 
houses in various parts of the country. One of these, I. iniquus subsp. 
nigellus, has received particular attention. For many years it was 
established in one of the greenhouses at the Bussey Institution, where 
Dr. Wheeler repeatedly observed it. This insect is now treated as a 
member of our ant fauna but the propriety of such treatment may be 
doubted. All records for nigellus have come from greenhouses or 
dwellings and there is nothing to indicate that this Costa Rican sub- 
species can endure the rigors of our winter climate even in the southern 
states. It might possibly do so in extreme southern Florida but, oddly 
enough, it does not appear to occur there. It seems to the writer that 
there is no more justification for treating nigellus as a member of our 
ant fauna than there would be for including the giraffes and kangaroos 
of our zoological parks in a list of North American mammals. On the 
other hand to omit nigellus from a comprehensive treatment of our 
ants would certainly lead to confusion. I have, therefore included this 
alien insect with our native ants. 

The habits of all the species of Iridomyrmex which occur in the 
United States are rather uniform. They are very active insects, despite 
their rather small size, and they prefer to forage in files. Although 
the ants in the files are close together they evidently follow a scent 



CKEIGHTON: ANTS OF NORTH AMERICA c$41 

path, for I have repeatedly observed that in the case of I. humilis 
the file can be thrown into great confusion by simply drawing a finger 
across the path. A 'traffic jam' immediately develops at either side 
of the patch of foreign scent and this persists until a few bold spirits 
have ventured across the finger mark and reestablished the proper 
scent trail. All our species nest in soil, although humilis will frequently 
move indoors during the winter months. The insects collect honeydew 
from various sources. They are also entomophagous. 



Key to the species of Iridomyrmex 

1. The antennal scape in repose surpassing the occipital margin by an amount 
equal to or somewhat greater than the length of the first funicular joint; 

the middle of the occipital margin flat or slightly convex 2 

The antennal scape in repose surpassing the occipital margin by an amount 
approximately equal to one-half the length of the first funicular joint; the 
middle of the occipital margin broadly but feebly impressed 3 

2. The greater part of the dorsum of the mesonotum bearing a flattened, 
irregular impression; mesoepinotal suture deeply impressed, the epinotum 
sharply set off from the rest of the thorax; appressed pubescence very 

dilute, the surface strongly shining iniquus subsp. nigellus 

Dorsum of the mesonotum unimpressed; mesoepinotal suture only moder- 
ately impressed, with the epinotum not notably set off from the rest of the 
thorax; appressed pubescence abundant, the surface feebly shining . . humilis 

3. Head and thorax with abundant, appressed, silvery pubescence which is 
dense enough to partially obscure the delicately shagreened surface be- 
neath; head and thorax usually sordid brown pruinosum 

Appressed pubescence on the head and thorax more dilute, revealing the 
rather shining surface beneath; color highly variable, deep brown to pale 
yellow pruinosum subsp. analis 



1 . IRIDOMYRMEX HDMILIS (Mayr) 
(Introduced) 

Hypoclinea humilis Mayr, Ann. Soc. Nat. Modena, Vol. 3, p. 164 (1868) 9 . 

Hypoclinea (Iridomyrmex) humilis Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, 
p. 959 (1870) 9 . 

Iridomyrmex humilis Forel, Ibid., Vol. 58, p. 395 (1908) cf; Newell, Jour. 
Econ. Ent., Vol. 1, p. 28 (1908) 9 9 cf; Newell, Ibid., Vol. 2, p. 182, 
fig. 4 a-c (1909) 9 9 cf ; Emery in Wytsman Genera Insectorum Fuse. 137, 
pi. 1, fig. 14, 14b (1912); M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 
No. 3, p. 590, pi. 16, fig. 62 (1947) 9 . 

Type loc: Buenos Aires, Argentina. Types: none in this country. 

Range: (in the United States) South Carolina west to Texas and south to 
Florida. California, particularly the southern half of the state. 



342 BULLETIN: MUSEUM or COMPARATIVE ZOOLOGY 

A great deal of effort has been expended on the control of this ant, 
since it is a serious pest in many southern areas. While humilis 
readily feeds upon sugary foods and can be held in check by the use 
of poisoned baits, such methods are usually not continued long enough 
to give a permanent relief from this pest. In the opinion of the writer 
there is evidence that in certain areas, formerly overrun by humilis, 
this insect is reaching a balance with our native ants. Thus in Mobile, 
Alabama, where the infestation was exceptionally heavy about twenty- 
five years ago, humilis at first dominated the area. Except for Pogono- 
myrmex badius and a species of Monomorium (probably viridum 
peninsulatum) the native ants were largely eliminated in the infested 
area. Later, however, the native species began infiltrating back into 
the infested area. By 1932 a considerable number of native species 
had reestablished themselves. This might have led to a balanced 
condition. But soon after there was a notable increase in the popu- 
lation of Solenopsis saemssima richteri, another importation from 
Argentina. This species is now as much of a pest as humilis formerly 



2. IHIDOMYRMEX INIQUUS NIGELLUS Emery 
(Introduced) 

I. iniquus var. nigella Emery, Bull. Soc. Ent. Ital., Vol. 22, p. 56 (1890) 9 . 
Typeloc: Costa Rica. Types: none in this country. 

Range: (in the United States) greenhouses in various parts of the country, 
particularly in the northeastern states. 



3. IRIDOMYRMEX PRUINOSUM (Roger) 

Tapinoma pruinosum Roger, Berl. Ent. Zeitschr., Vol. 7, p. 16 (1863) , , 

Emery, Zool. Jahrb. Syst., Vol. 8, p. 333 (1895) 9 ; Wheeler, Bull. Amer. 

Mus. Nat. Hist., Vol. 21, p. 389 (1905). 
Iridomyrmex pruinosus Wheeler, Bull. Mus. Comp. Zool. Harvard, Vol. 54, 

No. 17, p. 497 (1913) ? 9 . 
Tapinoma boreale Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 434 (1886) 9 

(nee Roger, nee Mayr 1866). 
Type loc: Cuba. Types: none in this country. 
Range: (in the United States) Florida and the eastern Gulf States west to 

Texas and New Mexico and North to Ohio and southern Wisconsin. 

There has been much confusion between this insect and its western 
subspecies analis. It is not possible to separate the two on the basis 
of color alone. The eastern pruinosum appears to be considerably 
more stable in coloration than analis, for the head and thorax of the 



CREIGHTON: ANTS OF NORTH AMERICA 6*6 

typical pruinosum are usually sordid brown. But both races may 
show the bicolored gaster which has been taken by many myrme- 
cologists as the distinguishing mark of analis. For this reason many of 
the eastern records attributed to analis probably belong to pruinosum. 
The size of pruinosum is slightly greater than that of analis and in 
pruinosum the head and thorax are distinctly more pubescent. The 
two races intergrade broadly in western Texas and New Mexico. 
Material coming from this region is particularly difficult to handle, 
since it is often impossible to assign it to either race. 



4. IRIDOMYKMEX PRUINOSUM ANALIS (E. Andre) 

Tapinoma anale E. Andre, Rev. Entomol., p. 148 (1893) 9 . 
T. pruinosum var. anale Emery, Zool. Jahrb. Syst., Vol. 8, p. 333 (1895). 
/. pruinosum var. testaceus Cole, Ent. News., Vol. 47, No. 5, p. 121 (1936) 9 . 
Type loc: Terraras, Chihuahua, Mexico. Types: none in this country. 
Range: California east to Texas, Oklahoma and Kansas. The northern limit 
of the range appears to lie in southern Idaho. 

There is little justification for the naming of the variety testaceus. 
The characteristics which supposedly distinguish testaceus are mainly 
those of color. It seems evident that when Dr. Cole described tes- 
taceus, he was unaware that analis is highly variable in color over its 
entire range. There are some specimens which are fully as dark as 
the eastern pruinosum and others which are even lighter than the 
types of testaceus. Since I have been unable to see that these color 
fluctuations have the slightest distributional significance, I believe 
that testaceus must be treated as a synonym of analis. 



Genus FORELITJS Emery 
(Plate 46, figures 1-4) 

The genus Forelius is a small New World group which is repre- 
sented in the United States by a single species, F. foetida. There have 
been a number of curious inconsistencies concerning the name of this 
species. For many years it was known as maccooki. Oddly enough, 
Forel, who first used this name in 1878, did so without any accom- 
panying description. Thus the first person who published a descrip- 
tion of maccooki was McCook himself. Nevertheless the name is 
generally credited to Forel. In subsequent years the insect was de- 
scribed several times under the name maccooki but in 1902 Wheeler 



344 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

published very strong evidence to show that this name had been 
applied to the insect which Buckley had described in 1866 as Formica 
foetida. It is probable that Buckley's description of foetida would have 
remained with those of his many unrecognizable species had it not 
been for the fact that he included in it a remarkably complete and 
accurate summary of the habits of the insect. He noted that the ants 
are very active, that they forage in files and often ascend trees, that 
they frequently construct craters at the nest entrance, that they have 
a disagreeable odor of rotten cocoanuts, which they emit when dis- 
turbed, and that they usually -have multiple queens in the nest. These 
observations had been of little use to the European specialists who 
had previously considered the probable nature of foetida. Their 
approach had been mainly from the morphological standpoint, 
which was unavoidable in view of their lack of field knowledge of 
our ants. In Wheeler's case the situation was different. His profound 
acquaintance with the habits of the ants of Texas enabled him to 
recognize that Buckley's foetida was the same insect that, since 1878, 
had been passing as maccooki. He therefore proposed the needed syn- 
onymy and shifted foetida to the genus Forelius. What happened 
thereafter is, to the writer at least, thoroughly inexplicable. In- 
stead of sticking to his synonymy Wheeler continued to use either 
name indiscriminately, and this singular and wholly unjustifiable 
practice appears to have been generally adopted. It even extended 
to the usually cautious Emery, who, when it was necessary to desig- 
nate the genotype of Forelius in the Genera Insectorum, cited both 
names with maccooki taking preference in the matter of position. 
Since in the body of that work he treated foetida as a valid species and 
made no question of Wheeler's synonymy of maccooki, his extraordi- 
nary citation in the case of the genotype constitutes one more incom- 
prehensible feature of this curious tangle. As things stand at present, 
maccooki is usually cited as the genotype of Forelius and this practice 
has certain advantages for Forel's types are presumably still in ex- 
istence and in any case there has never been the slightest question as 
to the insect he described as maccooki. But while one may laud this 
commendable caution in regard to Buckley's species, it would seem 
that in this case .conservatism is defeating itself. It has now been al- 
most half a century since Wheeler proposed to make maccooki a syn- 
onym of foetida. If this synonymy is unacceptable there has surely 
been ample time to prove it so. If this cannot be done, as seems to be 
the case, it is more than time that we stop using Forel's name mac- 
cooki. Its continuance is certain to add further confusion to a situa- 
tion for which there is neither logical explanation nor legal justifi- 



CKEIGHTON: ANTS OF NORTH AMERICA d4o 

The genus Forelius is remarkable in another respect, for it is one of 
the few genera whose certain definition rests upon an internal charac- 
ter. The sepals of the proventriculus are reflected, as is the case with 
most of the dolichoderine genera, but only the tips of these reflected 
sepals cover the bulb of the proventriculus. In this particular Forelius 
shows a distinct difference from Iridomyrmex (which it otherwise 
strongly resembles), since in the latter genus the reflected sepals are 
broadly appressed over the surface of the pro ventricular bulb. It may 
be taken as axiomatic that such characters have little appeal for most 
taxonomists. The technique of exposing the proventriculus is diffi- 
cult and the parts must be cleared before they can be properly studied. 
There is, in addition, the distasteful fact that the specimens so treated 
must be mutilated in the process. It is, therefore, a matter of grati- 
fication that for practical purposes foetida can be recognized without 
resort to the structure of the proventriculus. In foetida there are a 
number of short, erect, golden hairs which occur on the upper surface 
of the head, the dorsum of the thorax and to a less extent on the dor- 
sum of the gaster. Similar erect hairs are present on the antennal 
scapes and the tibiae. Since none of the species of Iridomyrmex which 
occur in the United States have the above hair pattern, it follows that 
this permits an easy separation for foetida. It should be borne in 
mind, however, that from the more general point of view the two 
genera must be separated on the structure of the proventriculus. 



1. FORELIUS FOETIDA (Buckley) 

Formica foetida Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 167 (1866) 9 9. 
Forelius foetida Wheeler, Trans. Texas Acad. Sci., Vol. 4, part 2, p. 24 (1902); 

Emery in Wytsman Gen. Insect. Fasc. 137, p. 35, pi. 1, fig. 18 (1912). 
Iridomyrmex maccooki Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 15, p. 382 (1878) 

(no description); McCook in Comstock, Rep. Cotton Insects, p. 187 

(1879) 9 ; Forel, Ann. Soc. Ent. Belg., Vol. 30, C. R., p. 39 (1886) 9 ; 

Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 432 (1886) 9 <?. 
Forelius maccooki Emery, Zeitschr. Wiss. Zool., Vol. 46, p. 389 (1888); M. R. 

Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 595, pi. 17, fig. 63 

(1947) 9. 

Type loc: central Texas. Types: none known to exist. 
Range: central Texas west to southern California and south into Mexico. The 

insect also occurs in Oklahoma and there are a few records from Kansas. 

The majority of the records are, however, from Texas, which appears to 

be the only part of the country where the insect is really abundant. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Genus DORYMYRMEX Forel 
(Plate 47, figures 1-4) 

The majority of the species belonging to the genus Dorymyrmex 
occur in South America, and the group is represented in the United 
States only by forms belonging to the species pyramicus. This insect 
has an extraordinary range. It occurs as far north as North Dakota 
and ranges southward as far as Argentina. The typical form is said 
to occur throughout the entire range. While this may be doubted, I 
shall presently attempt to show that it is best to allow this view to 
stand unquestioned for the present. In all parts of its range pyramicus 
has produced variants. Most of these are marked by differences of 
color and in certain cases the contrast is very striking. It is not sur- 
prising that these variants were soon noted and given varietal and 
subspecific names. This practice has resulted in certain difficulties. 
Because it is easier to deal with color than with structure, there has 
been little attempt to reinforce the color distinctions with more reli- 
able features based upon structure. The lack of any other separatory 
characters has caused considerable confusion as to the limits of the 
several variants. It will be clear to anyone who has examined the ob- 
servations published on pyramicus and its variants in the United 
States, that there is little agreement concerning the exact definition 
of these forms. What one author calls the variety nigra another will 
consider the typical pyramicus. Quite often the typical pyramicus 
appears suspiciously like the subspecies flaws. It is possible to intro- 
duce still more complication into the problem by utilizing, as Wlieeler 
did, Forel's subspecies brunneus. Although Wheeler never published 
on this form, there was much North American material in the Wlieeler 
Collection which he had assigned to it. On such a basis we would have 
to deal with the following arrangement: 

flamis McCook pale yellow 

pyramicus Roger sordid brownish yellow 

brunneus Forel deep brown 

nigra Pergande brownish black 

The arrangement may appeal to those who are not contented unless 
they have a name for every conceivable shade of color but from a 
practical standpoint it will not work. There is no sharp separation 
between these forms and good distinction can be secured only when 
extremes are compared. This observation is by no means based upon 
the writer's opinion alone. The literature abounds with references to 
intergrading conditions. 



CREIGHTON: ANTS OF NORTH AMERICA o4< 

It seems to the writer that the first step toward the solution of this 
difficulty was taken by Dr. M. R. Smith when he described the sub- 
species flavopectus. While the color of this insect was distinctive, Dr. 
Smith presented definitive structural features which are much more 
important. The cephalic and thoracic characteristics of flavopectus 
are those of a geographical race of pyramicus which occurs in Florida 
and throughout the southern parts of the eastern Gulf States. In 
point of fact the color of this subspecies is inconstant, for most of the 
specimens have the color supposedly characteristic of flamis. The 
structural features are, however, not only clear-cut but also remark- 
ably constant. This means that what we have been calling flavus is 
actually a composite of two different variants, the pale color phase of 
the typical pyramicus and the subspecies flavopectus. If flawpectus is 
marked by significant structural differences it is not unreasonable to 
suppose that comparable distinctions are present in other valid forms. 
Conversely, if there is nothing but a color difference to separate a form, 
its validity may be doubted. Unfortunately, this seems to be the 
case with several of them. Except for Wheeler's subspecies bicolor, 
which may be distinguished by its clypeal structure, there seems to 
be nothing but color which can be used to distinguish flavus, nigra or 
smithi from the typical pyramicus or, shall we say, from the form which 
has passed for the typical pyramicus among American myrmecologists. 
In an earlier paragraph I mentioned that there is room to doubt that 
the typical pyramicus occurs throughout the entire range of the spe- 
cies. From what has just been said concerning the taxonomy of this 
insect, it should be clear why such doubt may be entertained. Euro- 
pean myrmecologists no less than our own have become involved in 
the maze of color variants which have been assigned to pyramicus. 
Since neither Mayr nor Forel appear to have seen Roger's types there 
is little to indicate that their 'typical pyramicus' is the same insect 
that Roger described or the same form to which that name is applied 
here. It behooves us to tread very softly in this matter, however, for 
if our version of the typical pyramicus is not identical with Roger's 
Brazilian types, then we are faced with the necessity of resuscitating 
Buckley's name insana. For Buckley was undoubtedly the first to 
give a name to the dark variant of pyramicus which occurs over much 
of the southern and southwestern United States. Since this looks 
suspiciously like stepping out of the frying-pan into the fire, I believe 
that most myrmecologists will be content to leave matters as they 
are in regard to the typical pyramicus. 

Before leaving the taxonomy of Dorymyrmex, it is well to note 
that there seems little reason for the continued use of Forel's subgenus 
Conomyrma if Gallardo's genus Auracomyrmex is accepted. As I 



o4o BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

understand the matter, Forel's subgenera in Dorymyrmex were de- 
signed to take care of certain South American species which lack the 
epinotal tooth (tener, etc). With these removed to the genus Aura- 
comyrmex, all the remaining species would fall in Conomyrma, which 
would thus be coextensive with Dorymyrmex. 

Wheeler once described pyramicus as an 'alert and self-assertive' 
ant and it would be hard to improve upon this characterization. Our 
forms are noted for their tendency to nest in dry soil or sand in fully 
exposed areas where many species find the conditions intolerable. 
They will, on occasion, resort to the surprising practice of establish- 
ing their nest on the side of a mound built by Pogonomyrmex occiden- 
talis. No ant which was not alert and self-assertive could possibly 
hope to survive under such circumstances. The nests of pyramicus 
are usually surmounted by an irregular crater of excavated soil from 
two to four inches across. The ants are very active and predaceous 
but will feed on honeydew when they can get it. They have a strong 
odor of butyric acid which is particularly noticeable when they are 
crushed. 

Key to the subspecies of Dorymyrmex pyramicus Roger 

1. Mesonotum in profile rising through an even curve from the mesoepinotal 
suture, no abrupt declivious face present at the rear; occipital angles much 
rounded, only a small portion at the center of the occiput flat 

pyramicus subsp. flavopectus 

Mesonotum in profile rising abruptly from the mesoepinotal suture through 
a short, declivious, posterior face which forms a distinct angle with the 
more gently sloping dorsum; occipital angles only moderately rounded, the 
occiput flat or slightly concave for at least half the width of the head. . .2 

2. Clypeus broadly and evenly rounded without a trace of median angle or 
carina; head and thorax deep, reddish yellow, the entire gaster brownish 

black pyramicus subsp. bicolor 

Clypeus distinctly angular or subcarinate in the middle; color very variable 
but never as described above pyramicus 



1. DOEYMYRMEX PYRAMICUS (Roger) 

Prenolepis pyramica Roger, Berl. Ent. Zeitschr., Vol. 7, p. 160 (1863) 9 . 
D. pyramicus Mayr, Sitz. Akad. Wiss. Wien, Vol. 53, p. 394 (1886); Mayr, 

Verh. Zool-bot. Ges. Wien, Vol. 36, p. 365 (1886) 9 9 ; Emery, Zool. 

Jahrb. Syst., Vol. 8, p. 331 (1895) cf . 

Formica insana Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 165 (1866) 9 9 . 
D. flavus McCook, in Comstock, Rep. Cotton Insects, p. 188 (1879) 9 . 
D, pyramicus var. flavus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p 433 

(1886). 



CKEIGHTON: ANTS OF NORTH AMERICA d49 

D. pyramicus subsp. flavus Forel, Biol. Centrali Amer. Hym., Vol. 3, p. 103 
(1899) 9. 

D. pyramicus var. nigra Pergande, Proc. Calif. Acad. Sci. (2), Vol. 5, p. 871 
(1895) 9. 

D. pyramicus var. smithi Cole, Ent. News, Vol. 47, No. 5, p. 120 (1936) 9 . 

Type loc: Bahia, Brazil. Types: none in this country. 

Range: The range of the typical pyramicus in the United States is such a 
peculiar one that it cannot be summarized briefly. The insect is absent 
from the northeastern United States and its range begins in Illinois. To 
the west the range passes through Iowa, North Dakota, southern Montana 
and Idaho and the deserts of eastern Oregon. From this latitude south 
the range blankets the entire west. The range also runs southeastward 
from Illinois through Tennessee and the northern portions of Mississippi, 
Alabama and Georgia and the eastern part of South Carolina. The insect 
is exceedingly rare in the Gulf Coast region and Florida. There it is re- 
placed by the subspecies flavopectus. 

It seems well to note that the shape of the head in the typical 
pyramicus is subject to considerable variation. The occipital margin 
may be flat or broadly, although feebly, concave. The sides of the 
head are much more convex in some specimens than in others even in 
the same colony. There seems to be no connection between these 
variations and the color of the insect for they occur in both light and 
dark specimens. The thoracic structure, on the other hand, seems to 
be very constant (see key). 



2. DORYMYKMEX PYRAMICUS BicoLOR Wheeler 

D. pyramicus subsp. bicolor Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 22, 

p. 342 (1906) 9 . 

Type loc: Phoenix, Arizona (by present restriction). Types: M.C.Z. 
Range: western Texas to southern California. 

Although the range of the subspecies bicolor lies within that of the 
typical pyramicus, the two occupy separate stations because of the 
preference of bicolor for more arid nest sites. Mallis (1941) has con- 
tributed an interesting observation which has a bearing on this situa- 
tion. He has found that bicolor, despite the fact that it nests in hot 
and very arid areas, will forage regardless of the temperature, while 
the typical pyramicus will often remain in the nest during exception- 
ally hot days. There would seem to be no doubt that bicolor is better 
adapted to desert life than is the typical form. 



350 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

3. DOKYMYEMEX PYHAMICUS FLAVOPECTUS M. R. Smith 

D. pyramicus subsp. flavopectus M. R. Smith, Florida Entomol., Vol. 27, No. 1, 

p. 15 (1944) 9 . 
D. (Conomyrma) pyramicus subsp. flavopectus M. R. Smith, Amer. Mid. 

Naturalist, Vol. 37, No. 3, p. 596, pi. 17, fig. 64 (1947) 9 . 
Type loc: Archbold Biol. Sta., Lake Placid, Florida. Types: U.S.N.M. 
Range: Florida and the southern portions of Alabama and Mississippi. 

As I have already shown on a preceding page there has been con- 
fusion between this insect and the pale form of pyramicus which has 
been called flavus. It is possible that McCook's material contained 
specimens of flavopectus but, since most of it seems to have come from 
Texas, I do not think this is likely. While flavopectus is rather widely 
distributed in Florida its distribution in the eastern Gulf States seems 
to be limited to a narrow band about thirty miles wide extending in- 
land from the coast. This area is marked by the presence of turpentine 
pines and palmettos and the soil is very sandy. The insect may occur 
along the coast of Texas but all the pale specimens which I have seen 
from Texas have belonged to the typical pyramicus. 



Genus TAPINOMA Forster 
(Plate 48, figures 1-4) 

Our few representatives of Tapinoma are largely untroubled by 
taxonomic difficulties, except for the insect which Wheeler described 
as Bothriomyrmex dimmocki in 1915. Ten years later Emery was able 
to show that dimmocki belonged to the genus Tapinoma but Emery 
made no attempt to assess the specific status of dimmocki. In 1947 
Dr. M. R. Smith expressed the opinion that dimmocki might be nothing 
more than 'a pale, depauperate form of the common sessile.' It would 
considerably simplify matters if this proposition could be accepted but 
to do so involves certain discrepancies which are not easily explained. 
Chief among these is the remarkably small size of the female of dim- 
mocki. This insect measures only 1.8 mm. in length and it is safe to 
assume that this was what misled Wheeler as to the generic affinities 
of dimmocki. Certainly the female of dimmocki is notably smaller 
than that of sessile. Dr. Smith, who has made an exceptionally care- 
ful study of sessile, gives the length of its female as 3.75-4.29 mm. 
But there are other differences which distinguish dimmocki from ses- 
sile. The clypeus of dimmocki has a sinuate rather than a clearly 
incised anterior border. The one type female with wings lacked the 
discoidal cell which is present in sessile. Both these latter character- 



CREIGHTON: ANTS or NORTH AMERICA ooi 

istics not only separate dimmocki from sessile but place it with the 
species in the melanocephalum group. It may be admitted, however, 
that the worker of dimmocki is not strikingly different from that of 
sessile and the difference in wing venation may prove inconstant when 
more material is available. Dr. Smith may, therefore, be correct in 
his view of dimmocki but, until it can be shown that the differences 
which mark the female are of no significance, it seems safer to treat it 
as a separate species. 

Before turning to the habits of our representatives of Tapinoma, 
some cognizance must be taken of Wheeler's use of the subgenus 
Micromyrma. Originally Micromyrma was a generic synonym for 
Tapinoma which Dufour created in 1857. In 1887 Emery proposed 
to resuscitate Dufour's name to apply to a subgenus of Tapinoma 
which would include the species of the melanocephalum group. This 
proposal was made without knowledge that Dufour's Micromyrma 
was based upon the species erraticum, as is Tapinoma. In 191 1 Wheeler 
established this fact when he published his paper on the type species 
of ants. Emery promptly dropped the subgenus Micromyrma but, 
oddly enough, Wheeler continued to use the subgenus for the rest 
of his life, although his work had clearly shown that it is improper to 
do so. 

The habits of sessile have been exhaustively studied by Dr. M. R. 
Smith, whose account was published in 1928. Dr. Smith was able to 
determine that the average size of the colonies of sessile is between 
two thousand and five thousand individuals. The colonies are strongly 
pleometrotic with some colonies containing as many as two hundred 
dealated females. Dr. Smith believes that mating sometimes takes 
place in the nest and that this accounts for the large number of fertile 
females in a single colony. T. sessile is not at all particular about its 
nest sites and will nest in the soil, with or without a covering object, 
under bark and in all sorts of preformed cavities. It will also nest in 
houses and at times becomes a pest. Its elevational tolerance is re- 
markable. The insect occurs from sea level to sub-alpine areas. Ac- 
cording to Dr. Smith the insect frequently changes its nest sites. 
The workers usually forage in files and are omnivorous although they 
appear to prefer honey-dew and sweet foods when they can get them. 

The habits of the introduced melanocephalum are very similar to 
those of sessile but littorale seems to be a more arboreal species. It 
nests in hollow twigs, in the bases of epiphytes and in large, hollow, 
grass stems. It sometimes makes a carton entrance to the nest. It 
seems to feed mainly on honeydew secured from the secretions of 
aphids and coccids. While all three species are very energetic and not 
in the least timid they are less combative and bad tempered than 



ooz BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

many ants. This probably accounts for the fact that they will, on 
occasion, form compound nests with other ants. All three species 
have the typical 'tapinoma odor' of butyric acid. Nothing is known 
about the habits of dimmocki. 



Key to the species of Tapinoma 

1. Antennal scapes not quite reaching the occipital border; color pale yellow 

to sordid yellow littorale 

Antennal scapes surpassing the occipital border; color never as pale as 
described above 2 

2. Gaster white or pale whitish yellow, distinctly lighter than the deep brown 

head and thorax melanocephalum 

Gaster brown or brownish black, as dark or a little darker than the head 
and thorax 3 

3. Anterior margin of the clypeus distinctly excised in the middle; length of 

worker 2-3 mm., that of female 4 mm sessile 

Anterior margin of the clypeus sinuate in the middle but not distinctly 
excised; length of worker 1.8 mm., that of female 1.8 mm dimmocki 



1. TAPINOMA DIMMOCKI (Wheeler) 

Bothriomyrmex dimmocki Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 417 (1915) 9 9. 

Type loc: Mt. Tom, Springfield, Massachusetts. Types: M.C.Z. 
Range: known only from type material. 



2. TAPINOMA LITTOBALE Wheeler 

T. littorale Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 109 (1905) 9 9 c?. 
Type loc: Bahama Islands. Types: A.M.N.H., M.C.Z. 
Range : southern Florida, Bahamas, Puerto Rico, etc. 



3. TAPINOMA MELANOCEPHALUM (Fabricius) 
(Introduced) 

Formica melanocephala Fabricius, Ent. Syst., Vol. 2, p. 353 (1793) 9 . 

T. melanocephalum Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 651 (1862); 

Forel, Mitt. Miinchen Ent. Verh., Vol. 5, p. 3 (1881) 9 ; Emery, Ann. 

Stor. Nat. Genova, Vol. 24, p. 249 (1887) 9 c? ; Forel, in Grandidier Hist. 

Madagascar, Vol. 20, p. 104 (1891) 9 9 ; Bingham, Fauna Brit. India, 

Hym., Vol. 2, p. 304 (1903) 9 . 

Formica melanocephala Latreille, Fourmis, p. 269 (1802) 9 . 
Formica nana Jerdon, Madras Jour. Lit. Sci., Vol. 17, p. 125 (1851) 9 . 



CREIGHTON: ANTS OF NORTH AMERICA 606 

Myrmica pellucida F. Smith, Jour. Proc. Linn. Soc. Zool., Vol. 2, p. 71 (1857) 9 . 
Formica familiaris F. Smith, Ibid., Vol. 4, Sup. p. 96 (1860) 9 . 
Micromyrma melanocephalum Roger, Berl. Ent. Zeitschr., Vol. 6, p. 258 

(1862) 9 9. 

Type loc: Cayenne. Types: none in this country. 
Range: (in the United States) Florida only. 

Although there seems to be no reason why this tropicopolitan spe- 
cies should not occur in many areas in the southern United States, 
its range appears to be limited to Florida. There it seems to be re- 
stricted to the southern part of the state for as yet no records from 
stations north of St. Petersburg have been published. 



4. TAPINOMA SESSILE (Say) 

Formica sessilis Say, Bost. Jour. Nat. Hist., Vol. 1, p. 287 (1836) 9 . 

T. sessilis F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 57 (1858). 

T. sessile Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 434 (1886); Emery, 

Zool. Jahrb. Syst., Vol. 8, p. 332 (1895) 9 d"; M. R. Smith, Ann. Ent. 

Soc. Amer., Vol. 21, p. 309, pi. 18, figs. 1-3 (1928) 9 9 cf; M. R. Smith, 

Amer. Mid. Naturalist, Vol. 37, No. 3, p. 596, pi. 17, fig. 65 (1947) 9 . 
T. boreale Roger, Berl. Ent. Zeitschr., Vol. 7, p. 165 (1863) 9 9 ; Mayr, Sitz. 

Akad. Wiss. Wien, Vol. 53, p. 497 (1866) 9 . 

Formica gracilis Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 158 (1866) 9 9 . 
Formica parva Buckley, Ibid., Vol. 6, p. 159 (1866) 9 . 
Type loc: Indiana. Types: none known to exist. 
Range: southern Canada and the entire United States with the exception of 

desert areas in the southwest. The incidence of sessile appears to decrease 

sharply in the Gulf Coast region but it has been taken in Florida, Alabama, 

Mississippi and Texas. 



Subfamily FORMICINAE 

The majority of our species which belong to the Subfamily Formi- 
cinae are referable to the genera Formica or Camponotus. Although 
the Subfamily has only nine genera in America north of Mexico, there 
are so many species in the two genera just mentioned that the total 
representation in the Formicinae is only a little less than that in the 
Myrmicinae, where thirty-two genera are involved. While the struc- 
ture of the genera in the Formicinae is not strongly variable their 
habits are highly diverse. Generally this diversity cuts across generic 
or subgeneric lines. For example, there is temporary social parasitism 
in certain species of Formica and Lasius, although this characteristic 
is not found in all members of either genus. The capacity for pro- 



oo4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

ducing repletes is encountered in Prenolepis and many of the species 
of Myrmecocystus, yet a considerable proportion of the species in the 
latter genus appear to be carnivorous. Slave-making may be obliga- 
tory, as in Polyergus, or facultative, as in the case of certain species of 
Formica. An adaptation to an underground existence has been made 
in the case of Acanthomyops and certain species of Lasius, whose 
workers appear on the surface of the soil only at the time of nuptial 
flight. In such cases the ants usually tend root aphids and utilize the 
secretions of these insects as one of their main sources of food. The 
members of several subgenera of Camponotus show various degrees 
of adaptation to an arboreal life, culminating in the highly developed 
subgenus Colobopsis, whose bizarre major workers are among our most 
extraordinary ants. 

Before presenting the key to the genera I wish to comment on cer- 
tain departures from time-honored practices which it embodies. For 
the past half century it has been customary to utilize the relationship 
of the clypeal and antennal fossae as a distinguishing character for 
certain tribes and genera. The fossae are said to be either separate or 
confluent and the division has been based on this difference. There 
is no doubt that the distinction will apply clearly in certain cases. 
In Camponotus, where the antennae are ordinarily inserted well be- 
hind the posterior edge of the clypeus, the two fossae are usually 
separated by a low, rounded elevation whose posterior face bounds 
the front of the antennal fossa and whose anterior face descends to 
the suture at the rear of the clypeus. In Formica and Polyergus, 
where the scapes are always inserted close to the rear border of the 
clypeus, the reverse is true. The clypeal and antennal fossae are 
clearly confluent. It is somewhat ironical to note that, as far as our 
representatives are concerned, it is not necessary to utilize the differ- 
ence just mentioned to separate any one of the three genera. There 
are other and better characters by which they may be recognized. But 
the situation is altogether different in the case of the tribe Prenole- 
pidini. It is customary to separate this tribe from the Formicini be- 
cause of the supposed lack of confluence of the clypeal and antennal 
fossae in the former group. This practice has all the ear-marks of a 
desperation measure. The tribe Prenolepidini is a very difficult one 
to handle for it seems to have nothing but negative characteristics to 
mark it. This lack of distinction is equally true of the character of the 
clypeal and antennal fossae. In most of the species belonging to the 
Prenolepidini the frontal carinae are obscure and the fossae which they 
surmount are shallow and small. The front of the fossa is generally 
closed by the insertion of the antenna and, to this extent, it may be 
said that the antennal fossa is not confluent with the clypeal fossa. 



CREIGHTON: ANTS OF NORTH AMERICA d06 

But there is no distinct ridge separating the two, as in Camponotus, 
and the general configuration of the two fossae is more nearly like that 
of the Formicini. The attempt to utilize this character in the case of 
the Prenolepidini has not been a particularly happy one for it has 
given this character a bad reputation and damaged its value in those 
instances where it will clearly apply. I have made no attempt to em- 
ploy it in the following key because, from a practical standpoint, our 
few representatives of the Prenolepidini can be handled much more 
easily by using other separatory characters. 

I have also made a limited use of the position of the antennal in- 
sertions. The principal tribal character of the Camponotini is said to 
be the fact that the antennae are inserted well behind the posterior 
border of the clypeus. They usually are, but there are many exceptions 
to this rule. Most of the species in the genus Opisthopsis fail to show 
this character and there are several other exotic genera which fail to 
agree. Indeed the only genus in which the character appears to hold 
throughout is Polyrhachis. Most of our species of Camponotus agree 
reasonably well but, even within this limited segment of the group, 
there is considerable variation in the space which separates the in- 
sertion of the antenna from the posterior border of the clypeus. That 
we have been willing to accept this character as definitive for the 
Camponotini seems to indicate that for practical purposes we have 
been using other criteria as a means for recognizing the members of 
this tribe. I make no claim that the distinctions employed to separate 
Camponotus in the following key are generally applicable, but I do 
believe that they will give an easier and more certain separation than 
is possible if the position of the antennal insertion is used alone. 



Key to the Genera in the Subfamily Formicinae 

1. Antennae with nine segments Brachymyrmex 

Antennae with twelve segments 2 

2. Thoracic dorsum, in profile, evenly convex, the epinotum not depressed 
below the level of the promesonotum, the mesoepinotal suture unimpressed 
or very slightly impressed 1 ; mesothoracic spiracles borne on the sides of the 
thorax at a level well below the basal face of the epinotum; the antennal 
scapes usually inserted well behind the posterior edge of the clypeus 

Camponotus 

Thoracic dorsum, in profile, with the epinotum distinctly depressed below 
the level of the promesonotum; the impression at the mesoepinotal suture 
always distinct and often profound; mesonotal spiracles usually occurring 

J In certain species of the subgenus Colobopsia the epinotum is depressed and the meso- 
epinotal suture is rather strongly impressed, especially in the minor worker. In such cases, 
however, the head of the major is cylindrical and truncate anteriorly. 



356 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

in this impression on or close to the dorsal surface of the thorax; antennal 
scapes inserted at or near the posterior border of the clypeus 3 

3. Mandibles sickle-shaped, their inner border microscopically serrate; maxil- 
lary palps with four segments, labial palps with two segments . . . Polyergus 
Mandibles triangular with a distinctly dentate masticatory margin; maxil- 
lary and labial palps with a different number of segments 4 

4. Maxillary palps very short and consisting of three segments . . Acanthomyops 
Maxillary palps longer and consisting of six segments 5 

5. Maxillary palps longer than the head, the third and fourth segments very 
long; each of the above segments as long or longer than the two terminal 

segments combined; psammophore present Myrmecocystus 

Maxillary palps shorter, or at least no longer, than the head, the third and 
fourth segments not unusually long; psammophore absent 6 

6. Frontal carinae prominent, their lateral margins slightly reflected upward; 

ocelli very distinct Formica 

Frontal carinae poorly marked, their lateral margins flat; ocelli indistinct 
or absent 7 

7. Antennal scapes surpassing the occipital margin by at least one-third their 
length, usually much longer; erect body hairs coarse, long and usually 

brown or black in color 8 

Antennal scapes never surpassing the occipital margin by an amount greater 
than the length of the first funicular joint, often much shorter; erect body 
hairs not coarse, short and golden Lasius 

8. Thorax seen from above with the mesonotum very strongly compressed . . 

Prenolepis 

Thorax seen from above with the mesonotum only slightly compressed . . . 

Paratrechina 



Genus BRACHYMYRMEX Mayr 
(Plate 49, figures 1-4) 

The genus Brachymyrmex is composed entirely of species native to 
the New World. These tiny ants are easily transported in living plant 
material and two species (longicornis and heeri) were first described 
by Forel from colonies imported to European greenhouses. From a 
taxonomic point of view the genus is an exceptionally difficult one. 
The minute, highly specialized workers not only fail to show good 
separatory characters but are so constructed that ordinary methods 
of measurement often have little significance. The majority of the 
species of Brachymyrmex do not exceed 2 mm. in total length and 
many of them are only a little more than 1 mm. long. In addition to 
the small size, one must deal with a flabby and voluminous gaster 
which, in the living specimen, is usually about twice as long as the 
head and thorax. On drying the gaster may shrink to half of its for- 
mer length or may remain extended, though flattened. Under such 



CEEIGHTON: ANTS OF NORTH AMERICA oo 

circumstances it is easy to appreciate that over-all measurements of 
length, expressed in millimeters, have little meaning in the case of 
dried specimens. It seems likely that future work on the taxonomy of 
Brachymyrmex will involve measurement of the head and thorax in 
terms of microns. If the ensuing discussion appears hypercritical, it 
is not because of a lack of appreciation for the work of those who have 
dealt with this miserable little genus. It would appear, however, that 
the literature which treats of our two described forms is in consider- 
able need of revision. 

In 1893 Emery described depilis, which he made a subspecies of 
Forel's heeri. No specific type locality was cited for depilis but 
Emery observed that Pergande had sent him material from the Dis- 
trict of Columbia, Dakota, New Jersey and Virginia. Emery's char- 
acterization of depilis was of the briefest sort and consisted only of 
the statement that the new subspecies could be separated from the 
typical heeri by the complete lack of erect hairs on the thorax. It has 
been possible to avoid confusion in the case of depilis mainly because 
it is the only species which occurs in the northeastern United States. 
Ten years after depilis was described Wheeler set up a second species 
which he called nanellus. Wheeler's description of nanellus was ac- 
companied by a figure of the head of the worker as well as a figure of 
the head of a worker that Wheeler called depilis. I shall refer to these 
figures in a following paragraph for they played a large part in sub- 
sequent developments. No additional descriptive material covering 
either species appeared in the literature until 1923. In that year 
Santschi brought out his monograph on Brachymyrmex. In this mono- 
graph he raised depilis to specific rank and presented a short descrip- 
tion of the worker caste. The material on which this description was 
based was taken in North Carolina and identified by Forel. It may 
be noted that Santschi's description of depilis agrees well with speci- 
mens which come from the northeastern United States. 

What Santschi did with nanellus is quite another matter. It is 
obvious that he had no specimens that he could refer to this species 
and so he was forced to rely on Wheeler's description and figure. This 
would have been bad enough in itself, for both are inaccurate, but 
Santschi had the additional bad luck of misunderstanding Wheeler's 
description. Wheeler stated that the eye of nanellus has about six 
ommatidia in its greatest diameter. It is by no means easy to make 
exact counts of the number of ommatidia in the eye because those at 
the rim are often unpigmented and poorly defined. In any case there 
are always at least twenty well-defined ommatidia present and the 
number may run as high as forty when the eye is fully pigmented. 
In Santschi's description, however, the eye of nanellus was said to con- 



doo BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

sist of six facets. This error was repeated in the key, where nanellus 
is separated from myops because it has eyes consisting of eight (not 
six) facets, while the eye of myops has fifteen. For this mistake Sant- 
schi had himself to blame but he cannot be blamed for repeating other 
errors included in the original description and figure of nanellus. 
According to Wheeler, nanellus can be distinguished from depilis be- 
cause it is smaller, paler, with shorter funicular joints and shorter 
maxillary palps and the male is paler than that of depilis. To these 
five differences may be added a sixth which was shown in the figure. 
The occipital margin of nanellus is shown as feebly convex in marked 
contrast to the slightly concave occipital border of depilis. 

In preparing this work I have had occasion to examine a large 
number of specimens of Brachymyrmex coming from widely separated 
stations in the United States. Among these were the types of nanellus 
and other specimens identified by Wheeler as nanellus. The results of 
this study were discouraging for they strongly indicated that nanellus 
and depilis are specifically identical. Moreover, it soon became ap- 
parent that most of the criteria for the separation of nanellus which 
Wheeler cited are suspect. The occipital border of nanellus is slightly 
concave, not convex. The maxillary palps in nanellus are fully as long 
as those of depilis. The size range of the two appears to be identical 
and while I have seen no specimens of nanellus which are as dark as 
some of the eastern representatives of depilis, the latter form frequently 
throws pale variants which are fully as light as nanellus. I was at 
considerable pains to measure the funicular joints in the two forms, 
since the distinction there seemed to be a positive one that might 
permit specific separation. The funiculi are covered by dense, short 
hairs which reflect light and it is necessary, if accurate measurements 
are to be made, to immerse the insect in some liquid which will reduce 
the scattering of light by the hairs. For this reason the measurements 
cited below were not taken from type specimens. I believe, however, 
that they are reliable, since the specimens used had been compared 
with the types of nanellus. It may be recalled that Wheeler stated 
that funicular joints 2-6 were not longer than broad in nanellus. His 
figure is exceptionally confusing in this matter since the left funiculus 
shows these joints a little longer than broad while the right funiculus 
has joints three, four and five as broad as long. My measurements 
showed that funicular joints 2-6 are all slightly longer than broad with 
the exception of number three which is sometimes as broad as long. 
Exactly the same proportions were observed in the funicular joints of 
depilis. This led to the question of how Wheeler had been able to 
figure depilis with a funiculus in which the joints are notably longer 
than broad. I believe that in this figure lies the answer to the entire 



CREIGHTON: ANTS OF NORTH AMERICA day 

tangle. Unless I am very much mistaken, the insect which Wheeler 
regarded as depilis at the time when he described nanellus was actually 
heeri obscurior. This Mexican subspecies is slightly larger and notably 
darker than depilis and the funicular joints are distinctly longer than 
broad. In this connection it is worth noting that Wheeler stated that 
depilis is distinctly brown in color. This is certainly not the case with 
the material which I have examined. Even in fresh specimens the 
darkest individuals are sordid greyish or brownish yellow and certainly 
not brown. While it may seem unlikely that Wheeler should have 
confused obscurior with depilis, it is well to recall that up to 1903, 
when nanellus was described, most of Wheeler's myrmecological efforts 
had been confined to the ants of Texas and Mexico. His extensive 
studies of the ants of the eastern United States were still to come. It 
is, therefore, not improbable that he was better acquainted with 
obscurior than with depilis. 

In any case, I am convinced that nanellus cannot be regarded as a 
separate species nor do I think that it is subspecifically distinct from 
depilis. The only suggestive lead along this line appears to lie in the 
slightly larger eyes of some of the Texas specimens. The increased 
size of the eye is not due to a greater number of facets but rather to 
the greater size and wider spacing of the individual facets. As these 
individuals occur at random within a population having small facets 
in the eyes, no definitive range can be assigned to them. This variation, 
like that of color, apparently cannot be correlated with geographical, 
distribution. For the above reasons I have synonymized nanellus with 
depilis. 

1. BRACHYMTRMEX DEPILIS Emery 

B. heeri subsp. depilis Emery, Zool. Jahrb. Syst., Vol. 7, p. 635 (1893) 9 9 cf ; 

Wheeler, Psyche, Vol. 10, p. 103, fig. 7a (1903) 9 . 
B. depilis Santschi, Ann. Mus. Hist. Nat. Buenos-Aires, Vol. 31, p. 653, fig. 22 

(1923) 9. 
B. nanellus Wheeler, Psyche, Vol. 10, p. 102, fig. 7b (1903) 9 c7; Santschi, 

Ann. Mus. Hist. Nat, Buenos-Aires, Vol. 31, p. 664 (1923) 9 . 
Type loc: District of Columbia (by present restriction). Types: none in this 

country. 
Range: New England southward to Texas, New Mexico and Colorado. 



Genus CAMPONOTTJS Mayr 
(Plate 50, figures 1-6) 

Of the many subgenera now recognized as belonging to Camponotus 
only eight are represented in America north of Mexico. The over- 



360 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

whelming majority of our species are found in the four subgenera 
Camponotus, Tanaemyrmex, Myrmentoma and Colobopsis, with the 
remaining four, Myrmothrix, Manniella, Myrmaphaenus and Myrmo- 
brachys containing only seven forms among them. For this reason the 
last four subgenera offer little difficulty from a taxonomic standpoint. 
Unfortunately this is not true of three of the four subgenera in the 
first group for, with the exception of Colobopsis, the others are marked 
by much intricate and confusing taxonomy. Not only has there been 
need for considerable revision within these groups but it has also been 
necessary to revise the constitution of two of them. -I cannot agree 
with Emery's treatment of the subgenus Camponotus and, since the 
plan followed here differs from that proposed by Emery in the Genera 
Insectorum, I wish to consider briefly some of the steps by which 
Emery arrived at his arrangement. 

When the formicine section of the Genera Insectorum appeared in 
1925, it brought to a conclusion the revisionary work on the genus 
Camponotus which had been begun by Emery thirty years earlier. In 
1896 he had published a remarkably comprehensive plan for breaking 
up Camponotus into twenty-six subdivisions. These smaller units, 
which Emery called "maniples", were in many cases identical with our 
present subgenera. They were in large part based on a combination 
of structural and geographical considerations and it is to be regretted 
that Emery did not name them. Had he done so, much subsequent 
confusion might have been avoided. However, at that time the sub- 
genus was little used and Emery was content to leave his subdivisions 
nameless. In the first quarter of the present century the genus 
Camponotus underwent severe growing pains. It swelled to such 
unwieldy proportions that the subdivision of this vast agglomeration 
of species became imperative. At different times Ashmead, Wheeler, 
Forel, Emery and Santschi all published proposals to recognize sub- 
generic groups. Some of these suggestions were not very helpful, for 
both Wheeler and Ashmead would establish subgenera by simply 
designating a subgenotype, a practice which Emery later referred to 
as a "mode funestre anglo-americane". The bulk of the work fell upon 
Forel and Emery but even these two workers, who collaborated rather 
closely, did not always agree as to what species the various subgenera 
should include. The period from 1900 to 1920 was, therefore, a con- 
fused one as far as the subgenera of Camponotus were concerned, since 
the delimitation of the groups varied with the opinions of the several 
specialists involved. In 1920 the situation was materially improved 
when Emery published a very careful study in which the structural 
criteria of most of the present subgenera were given. This resolved 
much of the confusion and with the appearance of the formicine section 



CREIGHTON: ANTS OF NOHTH AMERICA ooi 

of the Genera Insedorum in 1925, an even better basis for general 
agreement was made available. There was good reason for profound 
satisfaction at Emery's masterly handling of this difficult matter for 
it stabilized the subgenera and largely put an end to the constant 
shifting about of species which had marked the earlier studies in this 
group. The widespread acceptance of Emery's scheme may be taken 
as proof that most myrmecologists regard the matter of stability as 
highly important, for Emery's arrangement is, in the last analysis, 
based in many cases upon an arbitrary division of intergrading groups. 
It is clearly impossible to secure sharp distinction between many of the 
subgenera, yet most students of ants have been willing to accept this 
fact for the sake of the stability and ease of handling which Emery's 
arrangement permits. I was fully prepared to do so in this work until 
it became necessary to bring up to date the keys for our species which 
Wheeler had presented in 1910. It then became apparent that Emery 
had made an error in his treatment of some of the North American 
species which he allocated to the subgenus Camponotus. It may be 
admitted that this subgenus intergrades with Tanaemyrmex and this 
gives a certain amount of leeway as to how the species are to be treated. 
But I believe that it can be shown that the structural relation of a 
number of the forms which Emery placed in Camponotus is with 
Tanaemyrmex. Emery himself originally recognized this relationship, 
for he described several variants in the sansaheanus complex, all of 
which he made subspecies or varieties of maculatus. Although Emery 
later placed maculatus in the subgenus Tanaemyrmex, only one of the 
variants (tortuganus) which he had previously assigned to it was so 
treated. The rest were shifted to the subgenus Camponotus. It seems 
peculiar that, if the structural similarity of these variants was close 
enough to allow them to be regarded as infraspecific forms of maculatus 
when first described, they should later be placed in a separate sub- 
genus. I do not propose that they be returned to maculatus but I do 
propose to place them in the subgenus Tanaemyrmex, where they 
properly belong. 

My view is based largely upon the cephalic structure in the two 
groups. In the species which I regard as belonging to the subgenus 
Camponotus the clypeus is ecarinate or so nearly ecarinate that it is 
difficult to discern more than a trace of median carina. The clypeal 
fossae are well developed, so that the clypeus stands out sharply from 
the lateral portions of the head which flank it. The antennal scapes 
are never flattened at the base. The head of the major worker is at 
least a little broader than long and often considerably broader than 
long. In the case of the species which I have transferred to Tanae- 
myrmex, there is less uniformity of structure. In general these species 



dO2 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY 

show a distinct median clypeal carina. In those which do not, the base 
of the antennal scape is flattened. The antennal fossae are usually 
shallow, particularly toward the top of the clypeus. Hence the clypeus 
is not so sharply separated from the flanking portions of the head as 
it is in the subgenus Camponotus. The head of the major worker is 
rarely broader than long. It may be as broad as long or, as is usually 
the case, notably longer than broad. Since these characters agree very 
closely with those of one type of major worker which Emery regarded 
as typical of the subgenus Tanaemyrmex (his /3 type worker), I cannot 
see why he felt it necessary to assign the species of the sansabeanus 
complex to. the subgenus Camponotus. 

It is also puzzling that Emery, who made such extensive use of 
geographical distribution in setting up subgenera in Camponotus, 
should have failed to appreciate the distributional difference which 
separates the North American representatives of Tanaemyrmex and 
Camponotus. In general, the subgenus Camponotus is boreal and 
eastern while our species of Tanaemyrmex are southern and western. 
There is remarkably little overlap in the two groups. Both occur 
together in the southeastern United States, particularly in the eastern 
Gulf States and Florida, but this is the only region where there is 
anything approaching an equal representation. Camponotus occurs 
widely throughout Canada, the northern and northeastern United 
States and at considerable elevations in the mountains in the western 
states. Representatives of Tanaemyrmex are absent or extremely rare 
in this region. Tanaemyrmex, on the other hand, abounds in dry or 
semi-desert areas in the southwestern and western states. It rarely 
occurs at high elevations in the western mountains, even in southern 
latitudes. The two groups are, therefore, more sharply separated than 
might be supposed from a hasty consideration of their distributional 
characteristics. I make no claim that the arrangement presented in 
this work represents an altogether satisfactory solution of the problem. 
I feel certain, however, that it checks more closely with facts of 
structure and distribution than does the plan presented by Emery in 
the formicine section of the Genera Insectorum. 



Key to the Subgenera of Camponotus 

1. Head of the major circular in cross section and abruptly truncated in front; 
the truncated portion consisting of the clypeus and adjacent parts of the 
cheeks with the mandibles forming the ventral segment; medias absent. . 

Subgenus Colobopsis 

Head of the major not circular in cross section and not abruptly truncated 
in front; if truncated the slant is oblique and involves the frontal lobes as 
well as the clypeus; medias present 2 



CREIGHTON: ANTS OP NORTH AMERICA 363 

2. Front of the head of the major obliquely truncate, the truncation involving 
the frontal lobes; clypeus flat and scarcely higher than the adjacent portions 

of the cheeks 3 

Front of the head of the major not obliquely truncate, more or less convex; 
clypeus convex or angular and distinctly higher than the adjacent portions 
of the cheeks 4 

3. Head of the major with a large, bordered, concave hollow at either side 
which extends across the cheek from the insertion of the antenna to the 

level of the middle of the clypeus Subgenus Manniella 

Head of the major without the concave hollow described above 

Subgenus Myrmaphaenus 

4. Scapes and legs with numerous, long, coarse, brownish or golden erect hairs 

on all surfaces Subgenus Myrmothrix 

Erect hairs on scapes and legs, when present, fine, short and usually whitish, 
often confined to a row of bristles on the flexor surface of the legs 5 

5. Thorax short, that of the major worker no longer than the head (mandibles 
excluded); humeral angles of the thorax well marked 

Subgenus Myrmobrachys 

Thorax longer, that of the major worker longer than the head (mandibles 
excluded); humeral angles of the thorax usually much rounded 6 

6. Anterior border of the clypeus feebly projecting, depressed in the middle 
and with a narrow, median notch, behind which is a short, triangular im- 
pression; length of the major worker at most 8 mm 

Subgenus Myrmentoma 

Anterior border of the clypeus not as above, usually without a median notch 
but when one is present there is no impression behind it; length of the major 
worker rarely less than 8 mm. and usually much more 7 

7. Clypeus ecarinate or scarcely carinate; antennal scapes never flattened at 
the base; clypeal fossae well marked; head of the major worker (mandibles 

excluded) at least a little broader than long Subgenus Camponotus 

Clypeus distinctly carinate or if feebly carinate the antennal scape is 
flattened at the base; antennal fossae shallow over most of their length; 
head of the major worker (mandibles excluded) as long as broad or distinctly 
longer than broad Subgenus Tanaemyrmex 



Subgenus CAMPONOTUS Mayr 

A considerable amount of revisionary work has been necessary in 
the case of this subgenus. I have referred elsewhere to the reasons 
which have led to the transfer of a number of species to Tanaemyrmex. 
Aside from these changes, there are others which have been necessary. 
Some of these arise from the practice of using the species herculeanus 
as a catch-all for any form whose exact status has been doubtful. 
Others stem from a lack of appreciation for the significance of color 
variation in several of the species. In early years little material was 



364 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

available and it is not surprising that some of these color variants were 
given varietal status. There is now no possible justification for this 
practice, yet it is still followed. Thus in 1936 Santschi set up a new 
subspecies of castaneus which he called rufinasis. This insect is an 
obvious synonym of the well-known americanus, whose highly variable 
coloration has been recognized and repeatedly commented upon since 
1862. Finally, I have found it necessary to transfer texanus and 
schae/eri to this subgenus. Actually texanus is a transitional species 
which links the subgenera Camponotus and Myrmentoma, hence its 
inclusion in either group is defensible. In my opinion, however, there 
is less chance for confusion if texanus is assigned to the subgenus 
Camponotus. 

The habits of the members of the subgenus Camponotus are not 
very uniform. Most of them build nests in decaying wood, which gives 
them their common name "carpenter ants". In this connection it 
seems worthwhile to note that the destructive capacities of these 
insects have been somewhat exaggerated. It is true that they fre- 
quently tunnel their nest passages in the timbers and wood-work of 
buildings and the excavations may be so extensive that large beams 
may be reduced to rotten shells. But it has been my experience that 
the V passages are rarely, if ever, driven into sound, dry wood. The 
presence of a nest of carpenter ants in the wood-work of a building is 
almost certain evidence that the infested area has been previously wet 
to the point of decay. The work of the ants has merely hastened a 
process of disintegration which would have ultimately occurred even 
if they had not been present. No properly constructed building in 
which the timbers are sound and dry is in any danger of ravages from 
carpenter ants. Because these ants excavate only the soft and rotting 
parts of the wood their nests which occur in logs or trees are often 
very diffuse, with the passages following areas of decay which may 
extend through many feet of sound wood. The species which nest in 
wood rarely make passages in the soil, even when the log containing 
the nest is partly buried. The reverse situation is true of americanus 
which nests by preference in soil. The nests are usually constructed 
under stones or fallen logs but in the latter case few of the passages 
enter the log. Our species belonging to the subgenus Camponotus may 
be separated as follows : 



Key to the species of Camponotus 

1. Major worker with the anterior margin of the median lobe of the clypeus 
straight or evenly concave, the angles which the median portion makes 
with the lateral portions sharp and tooth-like 2 



CREIGHTON: ANTS OF NORTH AMERICA ooo 

Major worker with the anterior margin of the clypeus not as described 
above, the anterior edge of the median lobe usually scalloped and meeting 

the lateral portions in blunt angles 3 

9 . Median lobe of the clypeus with a concave anterior edge in the major 
worker and female; head and gaster at least in part blackish, thorax and 

legs deep red texanus 

Median lobe of the clypeus with a straight anterior edge in the major 
worker and female; entire insect yellowish red schaeffen 

3. Antennal scapes with a number of short, scattered, erect hairs present; 
entire insect jet black and very shining, often with strong bluish reflections 

laevigatus 

Antennal scapes without erect hairs present except for a small cluster at 
the extreme tip; color not as above or, if uniform black, the surface is not 
strongly shining * 

4. The antennal scapes of the major worker reaching or barely surpassing the 

occipital corners herculeanus 

The antennal scapes of the major worker surpassing the occipital corners 
by an amount greater than their maximum diameter 5 

5. Pubescence on the gaster absent or very fine and sparse, the entire surface 

of the gaster distinctly shining 6 

Pubescence on the gaster coarse and dense, the surface of the gaster dull 
except for a narrow band at the posterior edge of each segment 7 

6. Punctures on the head coarse and conspicuous; head and gaster brownish 

black, thorax red noveboracensis 

Punctures on the head fine and inconspicuous; color very variable but the 
thorax never red americanus 

7. Pubescence on the gaster less than half as long as the erect hairs 

pennsylvanicus subsp. modoc 
Pubescence on the gaster about as long as the erect hairs 8 

8. Head, thorax, petiole and gaster dull black, pubescence pale yellow or 

white pennsylvanicus 

Posterior portion of the thorax, petiole and base of the first gastric segment 
bright, ferrugineous red; pubescence golden yellow 

pennsylvanicus subsp. ferruginea 



1 . CAMPONOTUS AMERICANUS Mayr 

C. americanus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 661 (1862) 9 9 . 

C. castaneus Mayr (part), Ibid., Vol. 36, p. 420 (1886). 

C. castaneus subsp. americanus Emery, Zool. Jahrb. Syst., Vol. 7, p. 674 

(1893) 9 ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 323 (1910) 9 9 cf. 
C. castaneus subsp. rufinasis Santschi, Rev. Entomol., Vol. 6, fasc. 2, p. 204 

(1936) 9 9. 

Type loc: New Orleans, Louisiana. Types: none in this country. 
Range: New England and southern Ontario south to the Gulf Coast and as 

far west as Iowa, Missouri, Oklahoma and Texas. 



dob BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

It is difficult to see why Wheeler was willing to accept Emery's 
treatment of americanus. The insect has little in common with 
castaneus which, in my opinion, belongs to the subgenus Tanaemyrmex. 
The head of the major worker of americanus is slightly broader than 
long and it lacks the very prominent median impression or excavation 
which is present in castaneus. The clypeus of the major is virtually 
ecarinate, although there is a small ridge immediately in advance of 
the frontal area which may represent the carina. Since Wheeler had a 
great deal of material of both americanus and castaneus in 1910 it 
seems scarcely credible that he should have failed to comment on the 
notable differences which distinguish these two insects. On the 
contrary he stated that he could find no difference other than a very 
slight distinction in the cephalic sculpture and the color of americanus. 
It is interesting to note that Wheeler would have reduced americanus 
to varietal status except for the fact that he could not find intergrades 
between it and castaneus. Since the ranges of the two insects are co- 
incidental over much of the eastern United States, this fact in itself, 
should have suggested that they are separate species. There is no 
room for doubt on this point and, while there may be some objection 
to the transfer of castaneus to the subgenus Tanaemyrmex, there can 
be none to according americanus the specific status which it deserves. 
I have already shown that Santschi's rufinasis is one of the innumer- 
able color variants which americanus throws over its entire range. 
There is nothing whatever to indicate that rufinasis is a geographical 
race and it must be regarded as a synonym of americanus. 



2. CA.MPONOTUS HEBCULEANUS (Linne) 

Formica herculeana Linue, Syst. Nat. Ed. 10, Vol. 1, p. 579 (1758) 9 ; Fabricius, 

Syst. Ent., p. 391 (1775); Fabricius, Ent. Syst., Vol. 2, p. 349 (1793); 

Fabricius, Syst. Piez., p. 395 (1804); Nylander, Acta. Soc. Sci. Fenn., 

Vol. 2, p. 894, pi. 18, figs. 1, 8 (1846) 9 9 cf ; Nylander, Ann. Sci. Nat. 

Zool. (4), Vol. 5, p. 56 (1856) 9 9 d 1 ; Schenk, Jahrb. Ver. Natur. Nassau, 

Vol. 8, p. 123 (1852) 9 9 d" ; Mayr, Verh. Zool-bot. Ges. Wien, Vol. 5, 

p. 308 (1855) 9 9 d". 
Camponotus kerculeanus Mayr, Europ. Formicid, p. 36 (1861); Forel, Fourmis 

Suisse, p. 39 (1874); Bull. Soc. Vaud. Sci. Nat., Vol. 16, p. 57 (1879); 

E. Andre, Spec. Hym. Europe, Vol. 12, p. 154 (1882); Emery, Zool. Jahrb. 

Syst., Vol. 7, p. 674 (1893); Ruzsky, Formicar. Imp. Ross, p. 214 (1905); 

Emery, Deutsche Ent. Zeitschr., p. 184 (1908); Forel, Fauna Ins. Helvet. 

Hym. Formicid, p. 68 (1915); Emery, Bull. Soc. Ent. Ital., Vol. 47, p. 225 

(1916); Bondroit, Ann. Soc. Ent. Fr., Vol. 87, p. 70 (1918). All the above 

references are for 9 9 d". 



CREIGHTON: ANTS OF NORTH AMERICA do/ 

C. herculeanus subsp. pennsylvanicus var. whymperi Forel, Trans. Ent. Soc. 

Lond., p. 699 (1902) 9 9 . 
C. herculeanus var. whymperi Emery, Deutsche Ent. Zeitschr., p. 184 (1908) 9 ; 

Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 330 (1910) 9 9 d" . 
? Formica semipunctata Kirby, Fauna Bor. Amer., Vol. 4, p. 262 (1837) 9 . 
? Camponotus semipunctatus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 13, p. 401 

(1863). 

Typeloc: Europe. Types: none in this country. 
Range: in North America, Alaska and Canada with southern extensions 

through the mountains in both the eastern and western United States. 

In the west this southern fringe extends to the mountains of New Mexico. 

In the east it apparently terminates in the mountains of Pennsylvania. 

Since Wheeler clearly demonstrated in 1910 that whymperi cannot 
be separated from the typical herculeanus, I can see no reason why he 
and other myrmecologistshave continued to recognize Forel's synonym. 
While it is convenient to have a name that distinguishes the American 
specimens of herculeanus from those of Europe, this is a poor excuse 
for a practice which is both misleading and contrary to the rules of 
nomenclature. In this volume whymperi has been treated as a synonym 
of herculeanus. 



3. CAMPONOTUS PENNSYLVANICUS (DeGeer) 

Formica pennsylvanica DeGeer, Mem. Hist. Insect., Vol. 3, p. 603, pi. 31, 
figs. 9, 10 (1773) 9 9 cf; Olivier, Encycl. Meth. Insect., Vol. 6, p. 501 
(1791); McCook, Trans. Amer. Ent. Soc., Vol. 5, p. 277, pi. 2-4 (1876). 

C. pennsylvanicus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 666 (1862) 9 9 ; 
E. Andre, Spec. Hym. Europe, Vol. 2, p. 141, 153 (1882) 9 9 . 

C. herculeanus subsp. pennsylvanicus Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 16, 
p. 57 (1879); Emery, Zool. Jahrb. Syst., Vol. 7, p. 675 (1893); Wheeler, 
Ann. N. Y. Acad. Sci., Vol. 20, p. 335 (1910) 9 9 d 1 ; M. R. Smith, Amer. 
Mid. Naturalist, Vol. 37, No. 3, p. 604, pi. 18, fig. 67 (1947) 9 . 

C. herculeanus var. herculeano-pennsylvanicus Forel, Bull. Soc. Vaud. Sci. Nat., 
Vol. 16, p. 56 (1879); Emery, Zool. Jahrb. Syst., Vol. 7, p. 668 (1893). 

C. herculeanus var. mahican Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 338 
(1910) 9. 

Type loc: Pennsylvania. Types: none in this country. 

Range: eastern United States and southern Canada as far west as the hun- 
dredth meridian and south to the eastern Gulf States. 



There are several reasons why pennsylvanicus must be given the 
specific status originally accorded it, although its long association 
with herculeanus makes this somewhat difficult. I believe that Forel 
was entirely incorrect in treating pennsylvanicus as a subspecies of 



368 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

herculeanus. In the first place the two insects are easily separable on 
the basis of scape length. The antennal scapes of herculeanus are 
much shorter than those of pennsylvanicus and there seems to be no 
evidence that this character intergrades. It may be recalled that 
Forel thought he had found intergrades between herculeanus and 
pennsylvanicus, to which he gave the name herculeano-pennsylvanicus. 
These supposed intergrades were, however, based entirely upon differ- 
ences in sculpture and pilosity. Moreover, they cannot possibly have 
been intergrades between the two insects for they were taken in an 
area (South Carolina) well to the south of the range of herculeanus. 
In my opinion these 'intergrades' clearly belong to the typical penn- 
sylvanicus and have no bearing on the problem of the behavior of that 
species and herculeanus. For if intergrades between these two species 
occurred one would expect to find them in the northeastern United 
States. The southern limit of the range of herculeanus reaches the 
mountains of Pennsylvania. There is thus a considerable area in the 
northeastern United States where that insect and pennsylvanicus co- 
exist. I have never seen the slightest indication that intergrades are 
produced in the above region. On the contrary the two insects appear 
to maintain their characteristics with remarkable clarity. In addition 
to the longer scapes of pennsylvanicus there is another difference 
shown by the females of the two insects. The female of pennsylvanicus 
is more heavily sculptured, with the head and thorax dull. The fe- 
male of herculeanus has a lighter sculpture, particularly on the thorax, 
which is almost as shining as that of noveboracensis in some specimens. 
The color of the female of herculeanus is rather variable but it usually 
shows considerable red on the thorax, which provides a further dis- 
tinction from pennsylvanicus, where the thorax of the female in the 
typical form is entirely black. 



4. CAMPONOTUS PENNSYLVANICUS FEBRUGINEA (Fabricius) 

Formica ferruginea Fabricius, Suppl. Ent. Syst., p. 279 (1798) 9 9 ; Latreille, 

Fourmis, p. 94 (1802). 

Camponotusferrugineus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 13, p. 399(1863). 
C. herculeanus subsp. pennsylvanicus var. ferruginea Emery, Zool. Jahrb. Syst., 

Vol. 7, p. 668 (1893); Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 338 

(1910) 9 9 cT. 

Type loc: 'America'. Types: none in this country. 
Range : northeastern states west to Illinois and south to Virginia and Tennessee. 

I have departed from the practice followed elsewhere in this work 
and retained ferruginea as a subspecies even though it is clear that it 



CREIGHTON: ANTS OF NORTH AMERICA doy 

is not a geographical race. The range of ferruginea is blanketed by 
that of the typical pennsylvanicus, yet the two insects show no ten- 
dency toward intergradation. Although the two behave as species I 
cannot, as yet, see anything except the striking and beautiful colora- 
tion of ferruginea by which they can be separated. Since color is such 
a notoriously bad separatory character in the case of ants, I do not 
care to consider ferruginea as a species on this basis alone. If subse- 
quent work reveals other differences, ferruginea will have to be given 
specific status. In the meantime it seems best to treat it as a sub- 
species. 

5. CAMPONOTUS PENNSYLVANICUS MODOC Wheeler 

C. herculeanus subsp. pennsylvanicus var. semipunctatus Forel, Bull. Soc. Vaud. 

Sci. Nat., Vol. 16, p. 57 (1879); Forel, Ann. Soc. -Ent. Belg., Vol. 48, 

p. 152 (1904) (nee Kirby). 
C. herculeanus subsp. modoc Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 333 

(1910) 9 9 d". 

Typeloc: California (by Wheeler's designation). Types: none in this country. 
Range: Pacific Coast States east to the Rockies. 

There is some question as to whether modoc ought to be considered 
as a race of pennsylvanicus for the ranges of the two insects do not seem 
to overlap. There are as yet no records of modoc from the east of the 
Rockies or any for pennsylvanicus west of the Dakotas. It is possible, 
however, that additional collecting in eastern Colorado and Wyoming 
may fill the gap. As far as structure is concerned, modoc seems very 
closely related to pennsylvanicus. The principal difference appears to 
lie in the shorter abdominal pubescence of modoc. 



6. CAMPONOTUS LAEVIGATUS (F. Smith) 

Formica laevigatus F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 55 (1858) 9 9 . 
C. laemgatus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 420 (1886) 9 9 ; 

Emery, Zool. Jahrb. Syst., Vol. 7, p. 671 (1893); Wheeler, Ann. N. Y. 

Acad. Sci., Vol. 20, p. 327 (1910) 9 9 d". 
Type loc: California. Types: British Museum. 
Range: Pacific Coast States east to the Rocky Mountains. 



7. CAMPONOTUS NOVEBORACENSIS (Fitch) 

Formica noveboracensis Fitch, Trans. N. Y. State Agri. Soc., Vol. 14, p. 52 

(1845) 9. 
C. herculeanus subsp. ligniperda var. pictus Forel, Bull. Soc. Vaud. Sci. Nat., 

Vol. 16, p. 59 (1879) 9 9 d"; Emery, Zool. Jahrb. Syst., Vol. 7, p. 674 

(1893). 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



C. herculeanus subsp. ligniperda var. noveboracensis Wheeler, Ann. N. Y. Acad. 

Sci., Vol. 20, p. 340 (1910) 9 9 cf . 
C. herculeanus subsp. ligniperda var. rubens Wheeler, Psyche, Vol. 13, p. 41 

(1906) 9 cf ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 341 (1910) 9 cf . 
Type loc: none given, by inference the State of New York. Types: none 

known to exist. 
Range: coast to coast, mainly in latitudes between 40 and 48. 

The taxonomic history of this insect has been singularly unfor- 
tunate. Fitch's description was overlooked by European specialists 
with the result that for many years the insect was known by Forel's 
name pictus. At that time Forel had reduced ligniperda to a subspecies 
of herculeanus. Since Forel attached pictus to ligniperda, it became 
a variety of herculeanus. But when ligniperda was finally restored to 
full specific status, pictus was allowed to remain as a variety of hercu- 
leanus. By this time pictus had been recognized as a synonym of 
noveboracensis. But while the change of names has been widely sanc- 
tioned, no one has seen fit to question the propriety of including nove- 
boracensis as an infraspecific variant of herculeanus. Actually the two 
insects show rather superficial similarities. In both the thorax of the 
female is more strongly shining than is usually the case in this sub- 
genus. In both the thorax of the worker is more or less marked by a 
red color. But against these common characters may be set differ- 
ences of much greater consequence. The antennal scapes of nove- 
boracensis are notably longer than those of herculeanus. In the major 
worker of noveboracensis the scapes surpass the occipital angles by an 
amount about three times as great as their maximum diameter. In 
addition the abdominal pubescence of noveboracensis is extremely fine 
and very dilute, so that the shining surface of the gaster is clearly ap- 
parent. In herculeanus the gastric pubescence is notably heavier and 
the surface of the gaster is dull, except for a feebly shining band at the 
rear of each segment. I do not believe that these two insects inter- 
grade, despite the fact that Wheeler described specimens from the state 
of Washington as intergrades between noveboracensis and herculeanus. 
As far as proximity is concerned, there is no reason why the two 
should not intergrade, for the southern end of the range of herculeanus 
overlaps that of noveboracensis in both the eastern and western states. 
It seems to me that the lack of intergrades in such areas furnishes a 
further proof that the two are separate species. Finally, I have found 
it necessary to synonymize Wheeler's variety rubens with novebora- 
censis. This form was described from a very few old and faded speci- 
mens. As no fresh specimens showing the coloration of rubens have 
ever been recorded it may be doubted that it is even a nest variety. 
The distributional data prove conclusively that it cannot be a geo- 
graphical race. 



CREIGHTON: ANTS OF NORTH AMERICA o/i 

8. CAMPONOTUS SCHAEFFERI Wheeler 

C. schaefferi Wheeler, Jour. N. Y. Ent. Soc., Vol. 17, p. 89 (1909) 9 9 ; Wheeler, 

Ann. N. Y. Acad. Sci., Vol. 20, p. 344 (1910) 9 . 
Type loc: Cochise Co., Arizona. Types: A.M.N.H., M.C.Z., Coll. W. S. 

Creighton. 
Range : mountains of southern Arizona, where it nests under logs at elevations 

of about 5000 feet. 

There are a number of points in the original description of schaefferi 
which are very confusing. The cotypes in my collection show no trace 
of transverse impression on the cheeks of the major. The sides of the 
head throughout most of their length are very slightly convex, al- 
though they curve inward suddenly near the insertion of the mandi- 
bles. The clypeus is neither flat nor is its anterior border distinctly 
excised in the middle. Instead, it is moderately convex with the mid- 
dle of the anterior border straight. The scapes of the major extend 
beyond the occipital corners by at least H their length. The frontal 
area is by no means indistinct and the V-shaped notch in the rear 
border of the clypeus, which lies just anterior to the frontal area, is 
very pronounced. The color and pilosity of this insect were accurately 
described. I have transferred this species to the subgenus Camponotus 
since the structure of the clypeus is more like that of Camponotus than 
Myrmentoma. When this insect and iexanus are better known it may 
be necessary to erect a separate subgenus for them. 



9. CAMPONOTUS TEXANUS Wheeler 

C. texanus Wheeler, Psyche, Vol. 10, p. 108, fig. 10 (1903) 9 9 cf ; Wheeler, 

Ann. N. Y. Acad. Sci., Vol. 20, p. 344 (1910) 9 . 
Type loc: Travis County, Texas. Types: A.M.N.H., M.C.Z. 
Range: central Texas in the region between Austin and San Antonio. 

This species, like schaefferi, has a clypeal structure which is more 
like that of Camponotus than Myrmentoma. In addition, its large 
size would make it exceptional in the latter subgenus. 



Subgenus TANAEMYRMEX Ashmead 

There have been so many revisionary changes in the case of species 
assigned to this subgenus that it seems advisable to present a sum- 
mary of the arrangement followed in this work. Before giving this 
list I wish to explain why such extensive revision was necessary. I 
have already discussed the reasons for shifting to Tanaemyrmex sev- 
eral species which Emery assigned to the subgenus Camponotus (see 



6(Z BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

discussion at the beginning of Camponotus) but while this shift con- 
fers distinct advantages in the matter of better subgeneric delimita- 
tion, it does nothing towards solving the difficulties of the tangle of 
variants which has grown up around the species sansabeanus. Orig- 
inally the sansabeanus complex was treated as a part of the even more 
formidable maculatus assemblage. The need for specific recognition 
within this fantastically intricate maze resulted in the splitting off of 
a number of species. One of these was sansabeanus. But with san- 
sabeanus removed from the specific limits of maculatus, the revisionary 
work on this highly confused tangle of variants largely ceased. Yet 
further revision is urgently needed. 

I have no wish to appear unduly harsh towards earlier work done on 
this very difficult complex but any careful examination of this work 
will bring the conviction that there has been too much stress laid on 
minor color variations and not enough attention paid to major struc- 
'tural differences or to geographical data. The practice of naming very 
slight color differences from inadequate series of specimens is to be re- 
gretted. Wheeler's variety luteangulus is an example of this practice. 
The type series of this variety consisted of about a dozen stray workers 
taken at four widely separated stations. It was, therefore, impossible 
to evaluate the constancy of the light colored blotches on the occipital 
corners of the major which supposedly distinguish this form. There 
is, unfortunately, no constancy in this character. At a conservative 
estimate more than fifty percent of all the members assigned to the 
sansabeanus complex will, at times, show such blotches. Hence lutean- 
gulus is not only unrecognizable but, what is worse, may be recog- 
nized in many nest series whose more significant characteristics clearly 
show them to be some other form. A number of the color variants 
previously assigned to sansabeanus show this same lack of constancy 
but this is by no means the worst feature involved. A much more 
serious situation arises from the fact that many of them have coinci- 
dental ranges. It may be admitted that in recent years the concepts 
concerning the distribution of subspecies have become much more 
stringent. Because of this, the older infraspecific groupings seldom 
meet modern requirements. Even so, it is seldom that myrmecolo- 
gists have elected to set up such a bewildering conglomeration of 
spatially coincidental subspecies and varieties as one finds in the 
sansabeanus complex. With the possible exception of the typical 
sansabeanus, there is not another variant in the complex which occu- 
pies a range to itself. Frequently three or four variants will occur to- 
gether over large areas. 

It is obvious that drastic steps are necessary to correct this situa- 
tion and it is equally obvious that such steps must involve consid- 



CEEIGHTON: ANTS OF NORTH AMERICA 616 

erable synonymization. The first step towards a solution was taken 
by Wheeler in 1917, when he recognized ocreatus as a separate species. 
I believe that it is necessary to accord specific status to vicinus and 
maccooki as well. The major part of the extensive synonymization 
has occurred in the case of color varieties previously assigned to 
vicinus. The arrangement used in this work is as follows : 

1. C. (Tanaemyrmex) acutirostris Wheeler 

= var. clarigaster Wheeler 
!. " " castaneus Latreille 

3. " " fumidus subsp. festinatus Buckley 

= subsp. spurcus Wheeler 

4. " " incensus Wheeler 
j. " " maccooki Forel 

= var. semitestacea Emery 
= var. berkeleyensis Forel 
= subsp. dumetorum Wheeler 
6. " " ocreatus Emery 

= subsp. primipilaris Wheeler 
'. " " sansabeanus Buckley 

I. " " sansabeanus subsp. bulimosus Wheeler 

9. " " sansabeanus subsp. torrefactus Wheeler 

10. " " socius Roger 

= var. osceola Wheeler 

11. " " tortuganus Emery 

12. " " mfer Wheeler 

13. " " vicinus Mayr 

= var. infernalis Wheeler 
= var. luteangulus Wheeler 
= var. maritimus Wheeler 
= var. nitidiventris Emery 
= var. plorabilis Wheeler 
= var. subrostratus Forel 

The variant of fumidus which Pergande named fragilis does not ap- 
pear in the above list. Wheeler was of the opinion that he had taken 
this insect in Texas but it seems clear from Wheeler's own data that 
what he had was the subspecies festinatus. I have never seen any 
specimens from the United States that could be assigned to fragilis 
and the fact that the types came from San Jose del Cabo and San 
Fernando in Lower California, argues against its occurrence within 
our borders. 

The habits of the ants of the subgenus Tanaemyrmex are rather uni- 
form. Most of the species nest in dry, gravelly soil. The nests are 



374 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

usually constructed under a covering stone but at times they may be 
surmounted by a low crater of earth. These ants rarely nest in wood 
and when they do the nest is usually buried under the soil. This proved 
to be the case with socius, an introduced species which has become 
widely spread in the eastern Gulf States and Florida. For several 
years I was unable to discover where this strikingly beautiful species 
nests, but ultimately found that the nests were built in branches and 
small rotten logs which had been entirely covered over by sand. I 
have never found them nesting in any other situation. 



Key to the species of Tanaemyrmex 

1. Antennal scapes with numerous, fine, short, erect hairs f 

Antennal scapes without erect hairs except for a cluster at the tip .... 3 

2. Anterior border of the clypeus broadly and feebly excised; erect hairs on 
the gula short and all of about the same length; mandibles with 5-6 teeth; 

length of the major 12-14 mm vafer 

Anterior border of the clypeus entire; erect hairs on the gula uneven in 
length, some of them long; mandibles with seven teeth; length of the 
major 8-10 mm fumidus subsp. festtnatus 

3. Middle and hind tibiae with a row of graduated, erect bristles on their 

flexor surfaces 5 

Middle and hind tibiae without such bristles ' 

4. Head and thorax subopaque; length of the major 10-11 mm. . .tortuganus 
The posterior corners of the head and the entire thorax feebly shining; 
length of the major 7 mm incensus 

5. Scapes of the major surpassing the occipital corners by an amount equal 

to or greater than the length of the first funicular joint 6 

Scapes of the major not surpassing the occipital corners, or surpassing 
them by an amount less than the length of the first funicular joint ... 11 

6. Scape of the major distinctly flattened at the base and with the flattened 

portion forming a small lateral lobule maccooki 

Scape of the major not flattened at the base or, if flattened, there is no 
lateral lobule 7 

7. The occipital corners covered with numerous, erect hairs; gaster com- 
pletely opaque socius 

The occipital corners without erect hairs; gaster feebly to strongly 
shining 8 

8. Cheeks strongly shining with very small, inconspicuous punctures 9 

Cheeks feebly shining or dull, the punctures coarser and conspicuous . . 10 

9. Thorax and gaster as strongly shining as the cheeks; color uniform 

castaneous brown castaneus 

Thorax and gaster less strongly shining than the cheeks; head black, 
thorax and gaster ochreous yellow, often suffused with brown, tibiae and 
tarsi brown to black ocreatus 



CKEIGHTON: ANTS OF NORTH AMERICA 375 

10. Scapes of the major flattened at the base; cheeks without erect hairs 

vitinus 

Scapes of the major not flattened at the base; cheeks with erect hairs. . . 

acutirostris 

11. Scapes of the major flattened and lobulate at the base 12 

Scapes of the major flattened at the base but not lobulate 

sansabeanus subsp. torrefactus 

1 2. Head reddish brown, thorax and gaster light, brownish yellow . sansabeanus 
Head black, thorax and gaster blackish or brownish red 

sansabeanus subsp. bulimosus 



10. CAMPONOTUS (TANAEMYRMEX) ACUTIROSTRIS Wheeler 

C. acutirostris Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 317 (1910) 9 9 cf . 
C. acutirostris var. clarigaster Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, 

p. 420 (1915) 9 . 

Type loc : Alamogordo, New Mexico. Types: M.C.Z., A.M.N.H. 
Range: low elevations in mountain canyons in New Mexico and Arizona. 

The variety clarigaster, which was described from a single specimen, 
was based upon extremely slight differences of color. There is, of course, 
no possibility of determining its validity under such circumstances and 
it is best treated as a synonym of the typical form. 



11. CAMPONOTUS (TANAEMYHMEX) CM 



(Latreille) 



Formica castaneus Latreille, Fourmis, p. 118, pi. 3, figs. 11, 12, A,C,D 

(1802) 990". 

Formica mellea Say, Host. Jour. Nat. Hist., Vol. 1, p. 286 (1836) <f . 
C. castaneus Mayr, Verh. Zool-bot. Ges. Wien, Vol. 36, p. 420 (1886);Wheeler, 

Ann. N. Y. Acad. Sci., Vol. 20, p. 321 (1910) 9 9 <?. 
C. melleus Mayr, Sitz. Akad. Wiss. Wien, Vol. 53, p. 485 (1866); Forel, Bull. 

Soc. Vaud. Sci. Nat., Vol. 16, p. 60 (1879) 9 9 <?.' 
Type loc: Carolina and Pennsylvania. Types: none in this country. 
Range : southern New England to the Gulf States. The western boundary of 

the range extends from Iowa to eastern Texas. 

Despite its long association with the subgenus Camponotus, there 
are sound reasons for transferring castaneus to the subgenus Tanae- 
myrmex. These have been obscured by the fact that americanus has 
been treated as a subspecies of castaneus. As I have explained else- 
where, the two insects have little in common. The head of the major 
worker of castaneus shows the distinct median incision of the clypeal 
border which is found in the species belonging to Tanaemyrmex. The 



o/b BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

head of the major is notably longer than broad. The clypeus is dis- 
tinctly carinate. Indeed, the only thing at all out of line with this 
treatment is the range of castaneus. It must be admitted that its pres- 
ence in the northeastern United States is exceptional for a member of 
the subgenus Tanaemyrmex. I believe, however, that it is better to 
accept this than to attempt to force castaneus into the subgenus Cam- 
ponotus. To do so destroys any chance of securing a good separation 
between that subgenus and Tanaemyrmex. 

12. CAMPONOTUS (TANAEMYRMEX) FUMIDUS FESTINATUS (Buckley) 

Formica festinatus Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 164 (1866) 9 9 . 
C. fumidus var. festinatus Wheeler, Trans. Tex. Acad. Sci., Vol. 4 (2), p. 22 

(1902); Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 312 (1910) 9 9 d"; 

M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 604, pi. 18, fig. 68 

(1947) 9. 

C. fumidus var. pubicornis Emery, Zool. Jahrb. Syst., Vol. 7, p. 670 (1893) 9 . 
C. fumidus var. spurcus Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 315 

(1910) 9 9. 

Type loc: central Texas. Types: none known to exist. 
Range: central Texas to southern Arizona and south into Mexico. 

I am unable to see why Wheeler set up the variety spurcus. As he 
himself noted, the subspecies festinatus is highly variable in coloration 
and he felt that additional material would show that the two are con- 
nected by "numerous transitional forms". This certainly seems to be 
the case. In my opinion the specimens from the western end of the 
range of festinatus are fully as light and as variable in coloration as 
are those from Texas. I have taken many colonies of this insect both 
in Texas and in the mountains of southern Arizona and I can detect 
no difference which would justify the recognition of a western race. 



13. CAMPONOTUS (TANAEMYRMEX) INCENSUS Wheeler 

C. (Tanaemyrmex) incensus Wheeler, Jour. N. Y. Ent. Soc., Vol. 40, p. 14 

(1932) 9. 

Type loc: Pigeon Key (Miami), Florida. Types: M.C.Z. 
Range: known only from type material. 

It seems impossible to state at present exactly what this form repre- 
sents. It was described from three specimens (one 'major' and two 
minors) and this gives a very inadequate picture of the insect. It 



CREIGHTON: ANTS OF NORTH AMERICA 6, 

may possibly be a synonym of iortugarms, which it strongly resembles. 
Indeed, the main difference between the two appears to be the smaller 
size of the major in incensus. It is impossible to decide, from the 
wholly inadequate type series, what the full size of the major of in- 
census is. Additional collecting in the Miami area may throw more 
light on this enigmatical form. 



14. CAMPONOTTJS (TANAEMYRMEX) MACCOOKI Forel 

C. sylvaticus subsp. maccooki Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 16, p. 69 
(1879) 9 9 d" . 

C. maculatus subsp. maccooki Emery, Zool. Jahrb. Syst., Vol. 7, p. 672 (1893); 
Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 306 (1910) 9 9 cf. 

C. maculatus subsp. vicinus var. semitestacea Emery, Zool. Jahrb. Syst., Vol. 7, 
p. 672 (1893) 9 ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 304 (1910) 9 . 

C. maculatus subsp. dumetorum Wheeler, Ibid., Vol. 20, p. 354 (1910) 9 cf. 

C. maculatus subsp. maccooki var. berkeleyensis Forel, Deutsche Ent. Zeitschr., 
p. 619 (1914) 9 . 

Type loc: Guadalupe Island, Lower California. Types: A.M.N.H. 

Range: Washington and Oregon south through California into Lower Cali- 
fornia. The insect is abundant only in the southern half of this range. 

There appears to have been considerable confusion concerning the 
differences which supposedly separate semitestacea and maccooki. 
When Emery described semitestacea he possessed only two workers. 
At this time he had a single worker media cotype of maccooki for com- 
parison. It is significant that Emery noted that both maccooki and 
semitestacea possess lateral lobes at the base of the antennal scapes. 
The separation which Emery used depended mainly on the fact that 
in maccooki the posterior part of the head was slightly more shining 
than in semitestacea. Wheeler, who mistakenly inferred that semitestacea 
lacked the antennal lobe, did not see any authentic material of this in- 
sect until after he had monographed our species of Camponotus. As 
a result he placed semitestacea with those forms which lack the anten- 
nal lobe and his key is highly misleading in this particular. Actually 
the only differences which separate semitestacea and maccooki are very 
slight distinctions of cephalic sculpture and color. I cannot see that 
either of these differences is sufficiently constant to permit successful 
separation. I am also of the opinion that maccooki has been described 
under different names by Wheeler and Forel. The characteristics on 
which Wheeler set up the subspecies dumetorum seem to be well within 
the range of variation shown by maccooki and, as Wheeler pointed out, 
Forel's berkeleyensis is a synonym of dumetorum. Until we know more 



378 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

about the distribution of maccooki in northern California, it seems 
preferable to treat all three variants as synonyms of the typical 
maccooki. 

15. CAMPONOTUS (TANAEMYRMEX) OCREATUS Emery 

C. maculatus subsp. ocreatus Emery, Zool. Jahrb. Syst., Vol. 7, p. 637 (1893) 9 ; 

Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 309 (1910) 9 . 
C. ocreatus Wheeler, Proc. Amer. Acad. Arts. Sci. Boston, Vol. 52, p. 561 (1917). 
C. acutirostris subsp. primipilaris Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, 

p. 319 (1910) 9 . 
C. ocreatus subsp. primipilaris Wheeler, Proc. Amer. Acad. Arts. Sci. Boston, 

Vol. 52, p. 562 (1917). 
Type loc: Panamint Mountains, California. Types: U.S.N.M., M.C.Z., 

A.M.N.H. 
Range: a discontinuous distribution in the mountains of southern California, 

Arizona and New Mexico. 

The characteristics which mark ocreatus are very distinct and it is 
unfortunate that Wheeler was not better acquainted with this species 
when he monographed Camponotus in 1910. At that time Wheeler 
failed to recognize the worker of ocreatus as such, but he redescribed 
it as a subspecies of acutirostris (primipilaris). Later WTieeler dis- 
covered type specimens of ocreatus and attempted to rectify his former 
error by transferring primipilaris to ocreatus. These two insects are 
so nearly the same that there is no justification for WTieeler's treat- 
ment. He should have made primipilaris a synonym of ocreatus. I 
believe that little significance can be attached to the clypeal structure 
of ocreatus, although Wheeler consistently cited this as an important 
separatory character. Although some major workers of ocreatus have 
an obtuse, triangular lobe at the middle of the anterior margin of the 
clypeus, this character never seems to hold over a nest series. There 
are much more constant features by which ocreatus may be recognized. 
The head of the major of ocreatus is notably narrowed in front of the 
eyes. The scapes surpass the occipital corners by an amount approxi- 
mately equal to the length of the first two funicular joints combined. 
The scapes show no trace of basal flattening. The cheeks are strongly 
shining. None of these characters would serve to distinguish ocreatus 
if taken alone, but the combination of them is unique. 



16. CAMPONOTUS (TANAEMYRMEX) SANSABEANUS (Buckley) 

Formica sansabeana Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 167 (1866) 9 9 d". 
C. maculatus subsp. maccooki var. sansabeanus Emery, Zool. Jahrb. Syst., 
Vol. 7, p. 672 (1893) 9 9 . 



CREIGHTON: ANTS OF NORTH AMERICA 379 

C. maculatus subsp. sansabeanus Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, 

p. 307 (1910) 9 9 <?. 
Type loc: Burnet and San Saba Counties, Texas. Types: none known to 

exist. 
Range: central Texas to Arizona and southern Colorado. 

17. CAMPONOTUS (TANAEMTHMEX) SANSABEANUS BULIMOSUS 
Wheeler 

C. maculatus subsp. bulimosus Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 308 

(1910) 9 d 1 . 
Type loc: Parmerlee and Huachuca Mountains, Arizona. Types: M.C.Z., 

A.M.N.H. 
Range: mountains of southern Arizona at elevations between 5000 and 6000 

feet. 



18. CAMPONOTUS (TANAEMYRMEX) SANSABEANUS TOHHEFACTUS 

Wheeler 

C. maculatus subsp. sansabeanus var. torrefactus Wheeler, Ann. N. Y. Acad. 

Sci., Vol. 20, p. 308 (1910) 9 cf. 

Type loc: Coconino Forest, Grand Canyon, Arizona. Types: M.C.Z. 
Range : northern Arizona and southern Utah. 



19. CAMPONOTUS (TANAEMYRMEX) socius Roger 

C. socius Roger, Berl. Ent. Zeitschr., Vol. 7, p. 140 (1863) 9 9 ; Forel, Bull. 

Soc. Vaud. Sci. Nat., Vol. 16, p. 74 (1879) 9 ; Mayr, Verh. Zool-bot. Ges. 

Wien, Vol. 36, p. 422 (1886) 9 ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, 

p. 319 (1910) 9 9 cf. 

C. socius var. osceola Wheeler, Jour. N. Y. Ent. Soc., Vol. 40, p. 15 (1932) 9 . 
Type loc. Brazil. Types: none in this country. 
Range: Florida and the southern portions of Georgia, Alabama and Mississippi. 

It is much to be regretted that Wheeler elected to describe the 
variety which he called osceola. The type series of osceola consisted 
of four specimens in which the red color of the head and thorax is paler 
and the gastric dorsum more yellow than is usual. While it may 
seem difficult to credit the idea that Wheeler described the color pat- 
tern of recently emerged workers, this appears to be the correct ex- 
planation. When osceola was described the material of socius present 
in the Museum of Comparative Zoology consisted of a considerable 
number of individuals taken singly or in very small series from a num- 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



ber of localities. All the evidence points to the assumption that these 
workers were taken while foraging. At least it can be stated with cer- 
tainty that if any of them were taken from a nest, only a fraction of 
the colony was secured. In the few nests of socius which I have found 
there have always been some paler workers whose coloration corre- 
sponds to that of osceola. Such individuals are well past the callow 
stage but they are not fully colored and do not voluntarily leave the 
nest. Hence they would not be present in a collection of workers taken 
while foraging. One may assume that the four specimens from which 
osceola was described were turned up by some accident to the nest. 
But to attribute nomenclatorial distinction to this immature color 
phase of socius is, in my opinion, impossible. 

One further point in connection with socius may be considered here. 
Its status as a member of our ant fauna presents an engaging problem 
to those interested in distributional phenomena. The original de- 
scription of socius was based on specimens taken in Brazil and it was 
not until some years later that the presence of this insect in the south- 
eastern United States was recognized. Since the species is absent in 
Mexico, Central America, northern South America and the Antilles, 
it is virtually certain that introduction has played a part in this un- 
usual distribution. The difficulty is to decide which of the two popu- 
lations is native and which is immigrant. It is generally assumed 
that the Brazilian population is the native stock but this is not easy 
to prove. At present socius is evenly distributed over most of Florida 
and the southern portions of Georgia, Alabama and Mississippi. As 
it is nowhere very abundant, there is nothing in its distribution in the 
United States to indicate that it is behaving as an introduced species. 
The same situation seems to be true of the Brazilian population. If 
socius has been introduced into the United States, it is now so at 
home in its new environment that it shows the characteristics of a 
native species. 

20. CAMPONOTUS (TANAEMYRMEX) TORTUGANUS Emery 

C. maculatus subsp. tortuganus Emery, Zool. Jahrb. Syst., Vol. 8, p. 336 

(1895) 9 ; Wheeler, Ann. N. Y. Acad. Sci., p. 310 (1910) 9 9 d 1 . 
Type loc: Dry Tortugas, Florida. Types: none in this country. 
Range: southern Florida through the Keys to the Tortugas. 

I have followed Wheeler in treating tortuganus as a separate species. 
The insect certainly cannot be assigned to maculatus and Emery's 
attempt to shift it to the species conspicuus was not satisfactory, even 
to him. The exact status of tortuganus will remain problematical until 
a thorough study of the Neotropical representatives of Tanaemyrmex 
is made. 



CREIGHTON: ANTS OF NORTH AMERICA c5l 

21. CAMPONOTUS (TANAEMTRMEX) VAFER Wheeler 

C. vafer Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 315 (1910) 9 9 . 

Type loc: Huachuca Mountains, Arizona. Types: M.C.Z., Coll. W. S. 

Creighton. 
Range: known only from type material. 



22. CAMPONOTUS (TANAEMTRMEX) VICINUS Mayr 

C. vicinus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 20, p. 940 (1870) 9 ; Forel, 

Bull. Soc. Vaud. Sci. Nat., Vol. 16, p. 60 (1879). 
C. maculatus subsp. vicinus Emery, Zool. Jahrb. Syst., Vol. 7, p. 671 (1893) 9 9 ; 

Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 301 (1910) 9 9 cf. 
C. maculatus subsp. vicinus var. nitidiventris Emery, Zool. Jahrb. Syst., Vol. 7, 

p. 672 (1893) 9 ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 304(1910) 9- cf . 
C. maculatus subsp. vicinus var. infernalis Wheeler, Ibid., Vol. 20, p. 305 

(1910) 9 c7. 
C. maculatus subsp. vicinus var. luteangulus Wheeler, Ibid., Vol. 20, p. 304 

(1910) 9 c?. 
C. maculatus subsp. vicinus var. maritimus Wheeler, Ibid., Vol. 20, p. 305 

(1910) 9 9 d*. 
C. maculatus subsp. vicinus var. plordbilis Wheeler, Ibid., Vol. 20, p. 303 

(1910) 99c?. 
C. maculatus subsp. vicinus var. subrostratus Forel, Deutsche Ent. Zeitschr., 

p. 620 (1914) 9 . 

Type loc: California (by present restriction). Types: none in this country. 
Range: the Rocky Mountains west to the Pacific, from British Columbia 

south into the highlands of Mexico. 

I have restricted the type locality of this species to California. In 
his original description of vicinus, Mayr used a mixed type series, 
only a part of which came from that state. Other specimens were 
taken in Connecticut, Virginia and New Mexico. The first two of 
these records are obviously incorrect. Wheeler was aware of this 
difficulty when he monographed Camponotus in 1910. Wheeler called 
attention to Mayr's error but made no attempt to restrict the type 
series of vicinus. It seems to me that it is imperative that this restric- 
tion be made. Otherwise the status of vicinus is jeopardized by the 
existence of type specimens which have nothing to do with the species; 

It seems unnecessary to discuss in detail the several varieties which 
have been placed in the synonymy of vicinus, for all but one of them 
can be covered by the same general statement. The color and pu- 
bescence of vicinus will vary over its entire range but there appears 
to be no correlation whatever between these variations and distribu- 
tion. For this reason there are always two or more of them present in 
the same area. It is certain that these differences are not of subspe- 



382 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

cific significance. These differences are too inconsequential and vari- 
able to be regarded as specific characters. The only possibility is to 
treat them as synonyms. In the case of the variety subrostratus, Forel 
has presented a description of the clypeus which strongly suggests 
that the insect is ocreatus. His brief description fails to mention any 
character which might confirm this surmise and there seems to be no 
way at present of determining the exact character of subrostratus. 
Since the variety was described from medias and minor workers, it 
may never be possible to arrive at a satisfactory treatment for it. I 
believe that it will save confusion if subrostratus is placed in the syn- 
onymy of mcinus until it can be shown that this is incorrect. 



Subgenus MYRMENTOMA Forel 

Of all the subgenera of Camponotus present in North America none 
is more difficult than Myrmentoma. There are intrinsic difficulties in 
this subgenus which cannot be avoided, but its taxonomy has been 
needlessly complicated by Wheeler's inclusion of texanus and schaefferi. 
In my opinion neither of these species can properly be regarded as be- 
longing to Myrmentoma. Their assignment to this subgenus has had 
the unfortunate effect of breaking down a clear-cut subgeneric diag- 
nosis. It may be admitted that superficially the two species suggest a 
relationship to Myrmentoma, but neither possesses a clypeus with a 
deep, narrow, median notch, which is the distinguishing subgeneric 
characteristic of Myrmentoma. It is always difficult to know what to 
do with transitional forms of this sort but it is my belief that both 
schaefferi and texanus present fewer incongruities if allocated to the 
subgenus Camponotus. They have been so treated in the present work. 
In the future it may prove advisable to erect a separate subgenus to 
receive them. 

With texanus and schaefferi removed from Myrmentoma, the sub- 
genus shows a much greater structural homogeneity. Indeed this 
very fact appears to be the main difficulty in the case of the caryae 
complex. Because the members of this large assemblage show com- 
paratively slight structural differences, it has been felt necessary to 
treat these differences as of no more than subspecific value. A sounder 
view of these distinctions might have been reached if Emery and 
Wheeler had been less concerned with giving names to varieties. 
When one encounters such varieties as Wheeler's pardus, pavidus and 
tanquaryi, each of which was described with the full knowledge that 
the definitive characters are highly variable, it is easy to secure the 
impression that a comparable situation marks all the members of the 
caryae complex. This is untrue. Most of the subspecies in this group 



CKEIGHTON: ANTS or NOKTH AMERICA 686 

have been founded upon constant distinctions related to cephalic 
sculpture and pilosity. These differences are entirely apart from the 
fluctuating and inconsequential variations which mark most of the 
varieties. Emery recognized these differences as early as 1893 and in 
1910 Wheeler utilized them to divide the caryae complex into two 
main groups. Yet neither Emery nor Wheeler ever considered the 
possibility that these differences might be of specific significance. In 
fact Wheeler appears to have lost sight of them. As Dr. M. R. Smith 
has shown, in 1917 Wheeler completely overlooked the characteristic 
cephalic sculpture and pilosity of Fitch's types of caryae. As a result 
he confused this insect with Emery's neardicus. Dr. Smith's revi- 
sionary paper of 1940 has clearly demonstrated Wheeler's error. It 
has also shown that Emery's variety cnemidatus is a synonym of Fitch's 
caryae. But this is as far as the revision of the caryae complex has 
gone. Dr. Smith's studies on Myrmentoma, which he mentions in 
his 1940 paper, have remained unpublished. No one regrets this more 
keenly than the writer. The circumstance has forced upon me the 
task of trying to put the caryae complex on an acceptable basis. I 
have discussed this matter with Dr. Smith and I believe that we are 
in agreement on the main features of the plan outlined below. Al- 
though this plan may appear, at first sight, to be drastically different 
from the older concept of the caryae complex, it embodies the main 
organizational features of the older system. The differences arise 
from an attempt to distinguish valid criteria (those formerly used to 
delimit subspecies) from invalid ones (those formerly applied to va- 
rieties). The structural constancy and distributional behavior of the 
former subspecies leaves no room for doubt as to their status. They 
must be treated as species, not as subspecies. There is, however, no 
such certainty as to what should be done with the varieties. In con- 
sonance with the practice employed elsewhere in this volume I have 
treated them as synonyms unless it could be shown that the variety 
has a geographical significance. Most of them plainly do not. We 
must, I believe, recognize the fact that over most of the eastern half 
of the United States the species neardicus produces a welter of color 
variations, any or all of which may occur in the same areas. There is 
not the slightest evidence to indicate that a single one of these variants 
has a range of its own and there is abundant evidence to show that 
they intergrade endlessly. Those who have a high regard for varietal 
names will find the synonymy of these variants distasteful. It should, 
however, produce one highly desirable result. Hereafter those who 
wish to use these varietal names can have no reason to complain of 
the difficulties which this practice involves. If they find these forms 
impossible of exact determination, if the keys which supposedly sep- 



oo* BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

arate them fail to do so, then it may be recognized that these are the 
penalties which must be paid for pushing a nomenclatorial system 
too far. For the sake of convenience I have included in the list which 
follows the full representation of the subgenus Myrmentoma in North 
America. 

1. C. (Myrmentoma) anthrax Wheeler 

2. C. (Myrmentoma) caryae Fitch 

= var. cnemidatus Emery 

3. " " caryae subsp. discolor Buckley 

4. " " " subsp. clarithorax Emery 

5. C. (Myrmentoma) essigi M. R. Smith 

6. C. (Myrmentoma) hyatti Emery 

7. " " " subsp. bakeri Wheeler 

8. C. (Myrmentoma) nearcticus Emery 

= var. decipiens Emery 
= var. minutus Emery 
= var. pardus Wheeler 
= var. paindus Wheeler 
= var. tanquaryi Wheeler 

9. C. (Myrmentoma) rasilis Wheeler 

10. C. (Myrmentoma) sayi Emery 

11. C. (Myrmentoma) subbarbatus Emery 

= var. paucipilis Emery ? 

The forms may be separated by means of the following key: 



Key to the species of Myrmentoma 

1. Mesoepinotal suture of the major and larger workers distinctly impressed, 
the impression broad and involving the rear of the mesonotum and the 

front of the epinotum 2 

Mesoepinotal suture of the major and larger workers unimpressed or, if 
a slight impression is present, it consists of a narrow, shallow, transverse 
groove on the dorsum of the epinotum immediately behind the suture . . 3 

2. Gaster entirely black or dark brown hyatti 

Basal two-thirds of the first gastric segment red hyatti subsp. bakeri 

3. Antenna! scapes of the major not surpassing the posterior corners of the 

head 4 

Antennal scapes of the major surpassing the posterior corners of the head 
by an amount at least as great as the greatest thickness of the scape. . . 5 

4. Color black, front of the head and the mandibles dingy red; the gaster 
coarsely shagreened and bearing conspicuous punctures; mandibles usually 

with 6 teeth anthrax 

Head and thorax yellowish red, only the gaster black; the latter finely 
shagreened with fine, piligerous punctures; mandibles with 4-5 teeth . . sayi 



CREIGHTON: ANTS OF NORTH AMERICA 385 

5. The majors and larger workers with numerous, short, erect hairs arising 

from coarse, oval f oveolae on the cheeks 6 

The foveolae on the cheeks of the majors and larger workers small and 
hairless 9 

6. Erect hairs on the cheeks and clypeus all of approximately the same length 

and of equal abundance 

Erect hairs on the clypeus notably longer and a little less abundant than 
those on the cheeks subbarbatus 

7. Head, thorax and gaster uniform piceous black caryae 

Head and thorax brownish red to reddish yellow, color of gaster variable 
but at least a part of it darker than the thorax 

8. Head and thorax clear brownish red, gaster uniform piceous black 

caryae subsp. discolor 

Head and gaster brown, the latter sometimes with yellow basal markings, 
thorax yellow, paler than the head and gaster . . . caryae subsp. clarithorax 

9. Frontal lobes rather strongly shining, their sculpture consisting largely of 
punctures, the shagreening very feeble; sides of the head in the major 
strongly convex and notably narrowed at the level of the mandibles . . essigi 
Frontal lobes feebly shining to opaque, distinctly shagreened in addition 
to the punctures; sides of the head in the major at most moderately convex 
and not unusually narrowed at the level of the mandibles 10 

10. Clypeus distinctly broader than long in the majors and larger workers; 
middle of the occipital border in the major straight or feebly concave, the 

occipital lobes not pronounced; color highly variable nearcticus 

Clypeus only slightly broader than long in the majors and larger workers; 
middle of the occipital border in the major distinctly concave, the occipital 
lobes well marked; head and thorax clear yellowish red, the gaster piceous 

rasilis 

23. CAMPONOTUS (MYRMENTOMA) ANTHRAX Wheeler 

C. anthrax Wheeler, Jour. N. Y. Ent. Soc., Vol. 19, p. 96 (1911) 9 9 cT. 
Type loc: Santa Inez Mountains, Santa Barbara, California. 
Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: known only from type material. 

The only data on the nesting habits of this species appears to be 
that which Wheeler published at the time of its original description. 
Wheeler took five nests of anthrax each of which was constructed in 
soil under large stones. If this type of nest is customarily built by 
anthrax, its habits certainly differ from those of most of the other 
species in this subgenus. 



24. CAMPONOTUS (MYRMENTOMA) CARYAE (Fitch) 

Formica caryae Fitch, Trans. N. Y. State Agr. Soc.,Vol. 14, p. 885 (1855) 9 9 cT. 
C. (M.) caryae M. R. Smith, Proc. Ent. Soc. Wash., Vol. 42, No. 7. p. 139, 
figs. 1, 2 (1940) 9 d" . 



oob BULLETIN:' MUSEUM or COMPARATIVE ZOOLOGY 

C. marginatus subsp. discolor var. cnemidatus Emery, Zool. Jahrb. Syst., Vol. 7, 

p. 678 (1893) 9 . 
C. fallax subsp. discolor var. cnemidatus Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, 

p. 232 (1910) 9 . 

Type loc: Salem, Washington County, New York. Types: U.S.N.M. 
Range: eastern New York south to the District of Columbia and west to Ohio. 

This insect appears to be rare. Dr. Smith makes no mention of 
other specimens beside the types of Fitch and Emery and the writer 
has seen no material belonging to it. Despite the paucity of records 
there would seem to be no reason why caryae may not be considered 
an eastern race, with discolor and darithorax representing central and 
western races of the same species. I believe that I am correct in 
stating that Fitch cited no locality at the time when he described 
caryae. It may be presumed that Dr. Smith secured this information 
from the locality labels of the type series. This insect appears to be 
associated with hickory trees. 



25. CAMPONOTUS (MYBMENTOMA) CARYAE DISCOLOR (Buckley) 

Formica discolor Buckley, Proe. Ent. Soc. Phila., Vol. 6, p. 166 (1866) 9 9 . 

C. marginatus subsp. discolor Emery, Zool. Jahrb. Syst., Vol. 7, p. 677 
(1893) 9 9 rf 1 . 

C. fallax subsp. discolor Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, p. 330 
(1910) 9 9 cf . 

Type loc: Central Texas. Types: none known to exist. 

Range: southern Alabama west to Texas and northward through the Missis- 
sippi Valley to Iowa, Illinois and southern Ohio. 

The writer has found this subspecies to be abundant in southern 
Alabama and it seems virtually certain that it must occur in north- 
western Florida. I have also seen specimens which Dr. Smith secured 
at Clemson College, South Carolina, se it seems probable that it also 
occurs sporadically both in that state and Georgia. These eastern 
records would, however, seem to lie outside the main range. 



26. CAMPONOTUS (MYRMENTOMA) CARYAE CLARITHORAX Emery 

C. marginatus var. darithorax Emery, Zool. Jahrb. Syst., Vol. 7, p. 678 

(1893) 9 9 cf 1 . 
C. fallax subsp. discolor var. darithorax Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, 

p. 231 (1910) 9 9 cf . 
Type loc: Los Angeles, California. Types: A.M.N.H., M.C.Z., U.S.N.M., 

Coll. W. S. Creighton. 
Range: known only from southern California. 



CBEIGHTON: ANTS OF NORTH AMERICA doY 

Wheeler has recorded this insect from Pennsylvania and Illinois but 
these records are almost certainly incorrect. Wheeler himself seems to 
have doubted them. Emery was of the opinion that the hairs and 
punctures on the anterior part of the head of clarithorax are less nu- 
merous than those of discolor. I have been unable to note much differ- 
ence in the types of clarithorax which I have examined. The main 
difference between the two forms appears to be one of color and, since 
the color of clarithorax is not particularly constant, it is by no means 
certain that clarithorax ought to be considered as a valid race. There 
is also the rather disconcerting fact that the range of clarithorax is 
widely separated from the western end of the range of discolor. It 
seems preferable, however, to treat clarithorax as a subspecies of caryae 
for it certainly shows no differences which would justify specific status. 



27. CAMPONOTUS (MYRMENTOMA) ESSIGI M. R. Smith 

C. caryae subsp. essigi M. R. Smith, Ent. News, Vol. 34, p. 306 (1923) 9 9 . 
Type loe: Lagunitas, California. Types: Coll. M. R. Smith, M.C.Z. 
Range: coastal area of central California. 

In the shape of the head the largest workers of this species strongly 
suggest those of anthrax. The head is very much narrowed at the 
level of the mandibles, with the result that the sides appear to be 
strongly convex. The scapes of essigi are, however, much longer than 
those of anthrax and the sculpture of essigi is feebler throughout. 
Mallis (1941) reports that he took this insect foraging in the debris at 
the edge of a salt marsh. 



28. CAMPONOTUS (MYRMENTOMA) HYATTI Emery 

C. hyatti Emery, Zool. Jahrb. Syst., Vol. 7, p. 680, pi. 22, figs. 25, 26 (1893) 9 ; 

Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 345 (1910) 9 . 
Type loo: San Jacinto, California. Types: A.M.N.H., M.C.Z., U.S.N.M. 
Range: central California. 



29. CAMPONOTUS (MYRMENTOMA) HYATTI BAKERI Wheeler 

C. hyatti subsp. bakeri Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 271 
(1904) 9 9 ; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 346 (1910) 9 9 . 
Type loc: Catalina Island, California. Types: A.M.N.H. 
Range: known from type material only. 



388 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Wheeler evidently regarded bakeri as an insular variant of the 
typical hyatti and he may be right. There seems to be no way at pres- 
ent to evaluate the status of bakeri. It was described from four speci- 
mens (two females and two media workers) and these appear to have 
been the only representatives of this form that have ever been secured. 
I have retained bakeri as a subspecies but I doubt that it will prove to 
be valid. Other 'insular subspecies' which Wheeler described from Cat- 
alina Island have since proven identical with the mainland form. 



C. marginatus var. neardicus Emery, Zool. Jahrb. Syst., Vol. 7, p. 675 

(1893) 9 9. 
C. fallax var. nearcticus Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, p. 222 

(1910) 9 9 <?. 
C. (M.) caryae subsp. neardicus M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 

No. 3, p. 604, pi. 18, fig. 70 (1947) 9 . 

C. caryae Wheeler, Psyche, Vol. 24, p. 27 (1917) (nee Fitch). 
C. marginatus var. decipiens Emery, Zool. Jahrb. Syst.,Vol. 7, p. 676(1893) 9 9 . 
C. fallax var. decipiens Wheeler, Jour. N. Y. Ent, Soc., Vol. 18, p. 227 

(1910) 9 9 d 1 . 
C. marginatus var. minutus Emery, Zool. Jahrb. Syst., Vol. 7, p. 676 

(1893) 99o". 
C. fallax var. minutus Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, p. 224 

(L910) 9 9 d 1 . 

C. fallax var. pardus Wheeler, Ibidem, p. 225 (1910) 9 9 d". 
C. fallax var. tanquaryi Wheeler, Ibidem, p. 226 (1910) 9 9 d". 
C. fallax rasilis var. pavidus Wheeler, Ibidem, p. 228 (1910) 9 9 . 
Type loc: Pennsylvania (by present restriction). Types: none in this country. 
Range: New England south to Florida and southwest to Texas. In the 

northern states the range terminates in the Dakotas but resumes again 

in the Pacific Northwest. There the insect occurs from British Columbia 

south to California with an eastward extension reaching Idaho. 

It seems scarcely necessary to present a detailed account of the rea- 
sons for synonymizing the varieties pardus, tanquaryi and pavidus. 
The unsatisfactory status of these varieties was apparent in the orig- 
inal descriptions which W'heeler presented in 1910. Each is based upon 
a slight distinction of color. Each is admittedly transitional in this 
respect. In each the definitive color characteristic was known to vary 
in the type series. In my opinion no one of the three should ever have 
been named. The situation with Emery's variety decipiens is some- 
what different. In 1941 Wheeler showed that decipiens had been based 
upon a mixed type series. The Texas types Wheeler considered iden- 



CHEIGHTON: ANTS or NORTH AMERICA ooy 

tical with his rasilis, hence to avoid Emery's prior name Wheeler re- 
stricted dedpiens to the Indiana types. In so doing he destroyed the 
principal distinction on which the recognition of dedpiens rested. Al- 
though Wheeler continued to recognize dedpiens, it is clear that the 
color characters which he employed will not allow a satisfactory separa- 
tion of this insect from nearcticus. Finally there is the variety minutus. 
Our younger myrmecologists have had little trouble with this variant 
for an excellent reason. They have with commendable uniformity 
let it severely alone. No other course is practical, since it is now clear 
that neither the size differences nor the coloration which Emery used 
to distinguish minutus can be relied upon. It seems clear enough that 
Emery's original delimitation of minutus was the result of a lack of 
adequate material but this will not excuse Wheeler's subsequent hand- 
ling of the form. Although Wheeler was clearly aware that no color 
distinction was possible in the case of minutus, and although he showed 
that there was no difference in the size of the male and too little in 
the size of the female and worker to give good separation, he con- 
tinued to defend this variety as a 'paler and depauperate form' of 
nearcticus! There is no wonder that our students of ants have despaired 
of recognizing this insect. 



31. CAMPONOTUS (MYRMENTOMA) BASILIS Wheeler 

C. fallax subsp. rasilis Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, p. 227 
(1910) 9 $ cf . 

Type loc: Austin, Texas (by present restriction). Types: A.M.N.H., M.C.Z. 

Range: Gulf Coast States from Florida to Texas and sporadically westward 
to southern Arizona. The northern limit of the range of rasilis is difficult 
to determine. It is abundant in the states bordering the Gulf of Mexico, 
but the incidence decreases rapidly to the north. The northern limit of 
the range appears to lie near Lat. 35 in the eastern and central states. 



32. CAMPONOTUS (MYBMENTOMA) SAYI Emery 

C. sayi Emery, Zool. Jahrb. Syst., Vol. 7, p. 679 (1893) 9 ; Wheeler, N. Y. 

Acad. Sci., Vol. 20, p. 343 (1910) 9 . 
Type loc: Phoenix, Arizona. Types: A.M.N.H., M.C.Z. 
Range: central Arizona. 

G. C. and E. W. Wheeler have reported this species from the bad- 
lands of North Dakota (1944) but the record is scarcely credible. We 
know little enough about the distribution of sayi but what we do know 



oyu BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

indicates clearly that the insect does not occur north of Arizona. De- 
spite much collecting it has never been taken in Utah or Colorado. 
That it should appear in western North Dakota seems absolutely im- 
possible. 



33. CAMPONOTUS (MYKMENTOMA) SUBBAEBATUS Emery 

C. marginatus subsp. subbarbatus Emery, Zool. Jahrb. Syst., Vol. 7, p. 676 

(1893) 9 9 d 1 . 
C. fallax subsp. subbarbatus Wheeler, Jour. N. Y. Ent. Soc., Vol. 18, p. 229 

(1910) 9 9 cf . 
C. marginatus subsp. subbarbatus var. paudpilis Emery, Zool. Jahrb. Syst., 

Vol. 7, p. 677 (1893) 9 d". 

Type loc: District of Columbia. Types: A.M.N.H., M.C.Z., U.S.N.M. 
Range: northeastern United States south to Virginia and west to Iowa. 

Since subbarbatus is so strictly confined to the northeastern and 
north central states, it is difficult to account for the specimens which 
Wheeler reported from Los Angeles. These had been sent him by 
Emery and were, in all probability, representatives of clarithorax. It 
is equally difficult to determine the exact character of paudpilis. 
Emery seemed inclined to regard this insect as an intergrade between 
subbarbatus and nearcticus. It seems to me, however, that this may be 
doubted. If these two species tended to intergrade, other specimens 
similar to paudpilis would certainly have been discovered, for the 
two species have virtually coincidental ranges over much of the north- 
eastern United States. It seems more logical to suppose that pau- 
dpilis represents nothing more than an abraded specimen of sub- 
barbatus in which some of the erect hairs on the genae had been rubbed 
away. It was, apparently, described from very few specimens and 
this may make it impossible of exact determination, even though the 
types are reexamined. Until more is known about this insect it seems 
inadvisable to attempt to separate it from subbarbatus. 



Subgenus COLOBOPSIS Mayr 

In both habits and structure the ants which belong to the subgenus 
Colobopsis are highly remarkable. The head of the female and that 
of the major worker resembles a cork, both in its shape and the use 
to which it is put. The head is virtually cylindrical with the anterior 
face abruptly truncated. If this truncated portion is viewed from 
directly in front, it will be seen to consist of the clypeus, the adjacent 



CREIGHTON: ANTS OF NORTH AMERICA oyl 

portions of the cheeks and the mandibles. The eyes, antennae and 
antennal lobes are not visible from this view of the head. To see them 
it is necessary to look at the upper surface of the head. The truncated 
anterior face of the head is often edged with a distinct raised rim and 
not infrequently the surface of the head within this rim forms a shal- 
low, saucer-like concavity. 

The insects nest in hollow twigs or galls and there is usually only 
one opening to the nest. This opening is circular and just large enough 
to permit the head of the major to be thrust into it like a loosely fitting 
cork in the neck of a bottle. The major worker thus acts as a living 
door which can be opened at appropriate intervals to permit the minor 
workers of the colony to leave or return to the nest. Wheeler has 
shown (1904) that the signal given by the returning worker which 
opens the "living portal" is a tactile one. When the head of the major 
is in the position to block the nest entrance, neither the eyes nor the 
antennae can function to receive stimuli from outside. Yet when the 
front of the head is touched by the antennae of the minor worker the 
"door" opens. Wheeler was unable to elicit this response by stroking 
the head of the "janitor" with a straw or pin. There is, therefore, 
probably more than a simple tactile response involved. Wheeler also 
presented good evidence to show that the nest founding female of 
Colobopsis occludes the nest opening in the same fashion as does the 
major. The group shows a further structural peculiarity in the ab- 
sence of the media workers. 

The ants of this subgenus are abundant only in the southern por- 
tion of the United States. A single species, cerberulus, is known from 
Arizona but the rest of the species are largely confined to a region 
which extends from Texas and Oklahoma eastward to the Atlantic. 
North of this region the abundance of these insects shows a notable 
decrease. Indeed, even within the area just mentioned, the incidence 
of the colonies appears to be greater in the southern portions of the 
range. In my opinion the abundance of these insects in the region 
north of the Gulf Coast is much greater than the records would indi- 
cate. The nests are always obscure and often wholly inaccessible to 
ordinary collecting. In addition to nesting in the hollow stalks of 
weeds and galls, many of the species prefer to nest in hollow twigs of 
living trees (hickory, pecan, white ash, etc.), hence the only satisfac- 
tory way to collect them is to examine the twigs when the trees are 
felled. I recall one occasion of this sort when I was able to go over the 
freshly cut limbs of trees which were being lumbered off in a swamp 
area near Taylorsville, Mississippi. In the course of two or three 
hours I secured more Colobopsis colonies than I had been able to find 
in several months of ordinary collecting. 



o9z BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Key to the species of Colobopsis 1 

1. Length of the major worker 3.75 mm. or less obliquus 

Length of the major worker 4.5 mm. or more 2 

2. The angle where the side of the head meets the truncated anterior face 
surmounted by a distinct, narrow flange or rim; sculpture of the anterior 

face consisting of small shallow punctures and fine reticulation 3 

The angle where the side of the head meets the truncated anterior face 
serrate or blunt but not surmounted by a distinct flange; sculpture of the 
anterior face coarsely punctate and heavily reticulate 4 

3. The flange at the lateral margin of the head with an almost perpendicular 
inner face, the area within the flange flat or nearly so; clypeus with a raised 

median strip of reticulo-rugose sculpture etiolatus 

The flange at the lateral margin of the head with a sloping inner face, the 
area within the flange notably concave; clypeus uniformly sculptured. . . . 

mississippiensis 

4. Punctures on the head of the major coarse but shallow, the angle between 
the side of the head and the truncate anterior face rounded and not serrate 

pylartes subsp. fraxinicola 

Punctures on the head of the major both coarse and deep, the angle between 
the side of the head and the truncate anterior face sharp and serrate 5 

5. Promesonotum of the major feebly convex in profile and no higher (some- 
times a little lower) than the dorsum of the epinotum; epinotum of the 
minor acutely angular with a deep impression at the mesoepinotal suture 

pylartes 

Promesonotum of the major moderately to strongly convex and always 
higher than the dorsum of the epinotum; angle of the epinotum in the 
minor rounded with the mesoepinotal suture only slightly or not at all 
impressed 6 

6. Crest of the petiole with a distinct concave impression in the middle; color 
golden yellow with only the posterior abdominal segments brown. . . hunteri 
Crest of the petiole flat or feebly convex; head and thorax reddish brown, 
abdomen piceous brown impressus 



34. CAMPONOTUS (COLOBOPSIS) CERBERULUS Emery 

C. (C.) cerberulus Emery, Bull. Soc. Ent. Ital., Vol. 52, p. 34 (1920) 9 ; Wheeler, 

Bull. Mus. Comp. Zool., Vol. 77, No. 5, p. 214 (1934) 21. 
Type loc: Michoacan, Mexico. Types: none in this country. 
Range: mountains of southern Arizona into Mexico. 

Emery described this species in 1920 from a single female taken in 
Mexico. It did not appear again in the literature until 1934. At that 
time Wheeler described what he regarded as the major worker of 

1 Emery's cerberulus^ does not appear in the key, as it is known from the sexual phases only. 
In 1934 Wheeler described what he believed to be the major of this species but, as his association 
is problematical, it seems less confusing to omit this little known species. 



CREIGHTON: ANTS OF NORTH AMERICA 6\)6 

cerberulus. The association was a roundabout matter. Wheeler had 
three major workers which were taken in acacia spines near Vera 
Cruz. These were similar to females coming from the mountains of 
southern Arizona. These were regarded as cerberulus by Wheeler. 
It may be that Wheeler is correct but this cannot be determined until 
a nest series containing all the castes has been secured. Until this can 
be done Wheeler's association is open to doubt. There is a further 
possibility that the females from southern Arizona are not cerberulus 
but an unnamed species. I strongly suspect that this is the case, for 
Emery's type came from the state of Michoacan, almost a thousand 
miles to the south of the Arizona border. Further study may show 
that cerberulus does not occur in the United States. 

35. CAMPONOTUS (COLOBOPSIS) ETIOLATUS WTieeler 

C. abditus var. etiolatus Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 150, 

fig. 5 (1904) 9-Ql 9 d"; Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 352 

(1910) 01. 
C. (C.) etiolatus Wheeler, Bull. Mus. Comp. Zool. Harvard, Vol. 77, No. 5, 

p. 216 (1934); M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 608, 

pi. 19, fig. 71 (1947) 21. 

Type loo: Austin, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: central Texas. 

Although W'heeler originally described etiolatus as a variety of ab- 
ditus, he later concluded that it is a closely related but distinct species. 
I have followed his suggestion in the present volume, but it should be 
borne in mind that there is nothing in our rather meager data on the 
distribution of these two insects which would prevent etiolatus from 
being regarded as a northern race of abditus. The two forms occupy 
wholly separate ranges, abditus occurring from Guatemala north into 
Mexico and etiolatus being confined to south central Texas.. When 
more is known of the ant fauna of northeastern Mexico, we may dis- 
cover, in that region, the junction of the two ranges. 



36. CAMPONOTUS (COLOBOPSIS) HUNTERI W r heeler 

C. (C.) pylartes var. hunteri Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 353 

(1910) 9. 

Typeloc: Victoria, Texas. Types: A.M.N.H., M.C.Z., Coll. W. S. Creighton. 
Range: known only from type material. 

In his original description of hunteri, WTieeler dealt entirely with 
color characteristics by which this form can be separated from py- 



oy-l BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

lartes. It is curious that he should have overlooked the strikingly dif- 
ferent thoracic structure of the two insects. In hunteri the epinotum 
is rounded, with the mesoepinotal suture unimpressed or nearly so, 
a condition which allies hunteri to impressus rather than to pylartes. 
It is certain that hunteri is not a color variety of pylartes and since it, 
pylartes and impressus all occur in eastern Texas without intergrada- 
tion, it seems necessary to treat hunteri as a separate species. 

37. CAMPONOTUS (COLOBOPSIS) IMPHESSUS (Roger) 

Colobopsis impressa Roger, Berl. Ent. Zeitschr., Vol. 7, p. 160 (1863) 9 ; Mayr, 
Verb. Zool-bot. Ges. Wien, Vol. 36, p. 423 (1886) 9 01. 

C. (C.) impressus Emery, Zool. Jahrb. Syst,, Vol. 7, p. 681 (1893) d"; Wheeler, 
Bull. Amer. Mus. Nat. Hist., Vol. 20, p. 144, fig. 3 (1904) 9 01 9 . 

Type loc: Georgia. Types: none in this country. 

Range: southeastern United States north to latitude 35 and west to central 
Texas. 

38. CAMPONOTUS (COLOBOPSIS) MISSISSIPPIENSIS M. R. Smith 

C. (C.) mississippiensis M. R. Smith, Psyche, Vol. 30, p. 83 (1923) 9 01; 

M. R. Smith, Ent. News, Vol. 35, p. 127 (1924) 21. 
Type loc: Starkville, Mississippi. Types: A.M.N.H., M.C.Z., Coll. M. R. 

Smith. 
Range: Mississippi and Alabama. 

39. CAMPONOTUS (COLOBOPSIS) OBLIQUUS M. R. Smith 

C. (C.) obliquus M. R. Smith, Ann. Ent. Soc. Amer., Vol. 23, p. 567 (1930) 01. 
Type loc: Starkville, Mississippi. Types: M.C.Z., Coll. Dept. Ent. A. & M. 

Coll. Miss., Coll. M. R. Smith. 
Range: known only from type material. 

40. CAMPONOTUS (COLOBOPSIS) PYLAETES Wheeler 

C. (C.) pylartes Wheeler, Bull. Amer. Mus. Nat. Hist.,Vol. 20, p. 147(1904) 9 9 . 
Type loc: Delvalle, Texas. Types: A.M.N.H., M.C.Z. 
Range: Gulf Coast region of Texas and Louisiana. 



41. CAMPONOTUS (COLOBOPSIS) PYLARTES FBAXINICOLA M. R. Smith 

C. (C.) pylartes subsp. fraxinicola M. R. Smith, Psyche, Vol. 30, p. 86 

(1906) 9 01. 
Type loc: Starkville, Mississippi. Types: A.M.N.H., M.C.Z., Coll. M. R. 

Smith. 
Range: Mississippi and Alabama. 



CKEIGHTON: ANTS OF NORTH AMERICA 6vo 

I have followed Dr. Smith in considering this insect as a subspecies 
of pylartes. It is, apparently, an eastern race of that species. 



Subgenus MYRMOTHRIX Forel 

The subgenus Myrmothrix is a comparatively small Neotropical 
group which is represented in the southern United States by two sub- 
species of the widespread abdominalis. The subspecies floridanus 
occurs not only in Florida but also, with decreasing frequency, along 
the Atlantic seaboard to North Carolina. Its western range seems 
much more sharply limited. In Alabama it appears to be confined to 
the area lying between the Perdido River and Mobile Bay. It should 
be present in that part of Alabama which lies immediately north of 
Florida, but if it occurs there it is very scarce. I have never been able 
to find floridanus in that part of Alabama which lies to the west of 
Mobile Bay, nor has Dr. Smith recorded it from Mississippi. This 
distribution suggests that floridanus originally entered the United 
States from the Antilles. Unfortunately for this theory, the nearest 
and only Antillean representative of abdominalis is the subspecies 
nocens, which occurs in Grenada. From a spatial standpoint, there- 
fore, the nearest relative of floridanus is the Texan subspecies trans- 
vectus. Although the ranges of the two are separated by a gap of more 
than five hundred miles, I believe that floridanus ought to be con- 
sidered as a subspecies of abdominalis. The structural differences 
which mark floridanus are in all respects comparable to those which 
distinguish the series of spatially adjacent forms which extend from 
northern Mexico to southern Brazil. 

Scarcely anything has been published on the habits of transvectus 
but those of floridanus are well known. The insect forms rather popu- 
lous colonies in and under rotten logs, stumps, etc. Occasionally the 
nests are begun under stones. It is an active, aggressive ant and has 
been reported as a pest of bee hives, which it enters and plunders. 
According to the writer's observation, floridanus prefers to nest in 
rather damp situations, such as the swales along stream bottoms, 
rather than on high, dry ground. 



Key to the subspecies of C. (Myrmothrix) abdominalis Fabricius 

1. Head entirely ferrugineous red; cheeks with small foveolae and without 

erect hairs abdominalis subsp. floridanus 

Head dark brown or black at the vertex; cheeks with deep, elongated 
foveolae and erect hairs abdominalis subsp. transvectus 



396 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

42. CAMPONOTUS (MYRMOTHRIX) ABDOMINALIS FLORIDANUS (Buckley) 

Formica floridana Buckley, Proc. Ent. Soc. Phila., Vol. 6, p. 161 (1866) 9 . 
C. atriceps var. floridanus Mayr, Verb. Zool-bot. Ges. Wien, Vol. 36, p. 223 

(1886) 9 9 d". 
C. abdominalis subsp. floridanus Emery, Zool. Jahrb. Syst., Vol. 7, p. 670 

(1893); Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 325 (1910) 9 9. 
C. (M.) abdominalis subsp. floridanus M. R. Smith, Amer. Mid. Naturalist, 

Vol. 37, No. 3, p. 604, pi. 18, fig. 69 (1947) 9 . 
C. atriceps subsp. yankee Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 20, p. 340 

(1884) 9 9 d 1 . 

Type loc: Florida. Types: none known to exist. 
Range: Florida, Georgia, South Carolina and the southeastern portion of 

Alabama. 

43. CAMPONOTUS (MYRMOTHRIX) ABDOMINALIS TRANS VECTUS Wheeler 

C. abdominalis transvectus Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 326 

(1910) 9 9 cf. 

Type loc: Harlingen, Texas. Types: M.C.Z. 
Range: the Brownsville region of Texas and northeastern Mexico. 

In the original description of transvectus the majority of the type 
series was said to have come from 'Harlington, Cameron County, 
Texas'. There is no such town in Cameron County and the name 
appears to have been an obvious misprint for Harlingen, a small town 
a few miles north of Brownsville. Wheeler also included Brownsville 
as one of the type localities of transvectus, since he had a single worker 
from that area. In this case it may seem pedantic to insist that only 
Harlingen be regarded as the type locality and that only the Har- 
lingen specimens be considered the types. I prefer to do so, however, 
since the practice of citing multiple type localities cannot be justified 
and is certainly apt to produce confusion. 



Subgenus MYBMOBRACHYS Forel 

The subgenus Myrmobrachys possesses only two forms whose 
northern range reaches the United States. One of these, mina subsp. 
zuni, occurs in southern Arizona. The other, planatus, is known from 
the Brownsville region of Texas and southern Florida. There has been 
a considerable difference of opinion as to the exact taxonomic status 
of specimens of planatus coming from the United States. American 
specialists have uniformly treated these as identical with the typical 
planatus, while European authorities have just as consistently re- 



CREIGHTON: ANTS OF NORTH AMERICA 6\)t 

garded them as belonging to the subspecies continentis. I wish to re- 
view certain aspects of this difficulty since, as things stand at present, 
the literature contains some very confusing contradictions which no 
one has attempted to resolve. To secure an adequate idea of the 
problem one must, of course, consider the entire range of planatus and 
not merely those attenuated portions of it which lie within our borders. 
This range is considerable, for planatus occurs widely in Cuba and is 
fairly abundant on the continent from Mexico to Colombia. In the 
southern part of this range four subspecific variants have been recog- 
nized, of which only the subspecies continentis is of particular concern 
to this discussion. The subspecies continentis was set up by Forel in 
1901 on the basis of material coming from Guatemala. There is fair 
evidence to show that Forel erected this subspecies without being 
aware of the exact nature of the typical planatus. Up to the year 1899 
Forel had treated planatus as a subspecies of senex and until that year 
he made no attempt to describe variations in the population of plana- 
tus. Once Forel had acceded to Roger's original concept of planatus 
as a separate species, he began to discover infra-specific variants in 
planatus, which he duly described and named. I do not wish to imply 
that these variants are without significance but I do wish to empha- 
size that Forel and later Emery, who also interested himself in the 
continental variants of planatus, would never have named them un- 
less they had believed them to be different from the insect which Roger 
had originally described. This may seem too obvious to require com- 
ment, yet it is the conviction that all the continental representatives 
of planatus are different from the typical Cuban form which is re- 
sponsible for most of the trouble. In 1910 Wheeler published a very 
full description of all the phases of planatus, together with comments 
which made it clear that specimens of this insect coming from the 
southern United States are identical with those found in Cuba and 
parts of -Mexico. In his description Wheeler took no cognizance of 
the described continental variants of planatus and, while he may have 
avoided a thorny issue by so doing, it seems clear that this neglect is 
what gave Emery the opportunity to treat Wheeler's description as 
that of the subspecies continentis rather than that of the typical plan- 
atus. At least this was what Emery did. 

We may count ourselves fortunate that Roger based the species 
planatus on specimens coming from Cuba. The insect is not only 
abundant throughout the whole island but shows a remarkable uni- 
formity of structure regardless of the station from which the speci- 
mens come. There can, therefore, be little question of races in the 
Cuban material and, if such material is available for examination, one 
may feel confident of the characteristics of the typical planatus with- 



dys BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

out reference to Roger's types. There is a substantial amount of 
planatus material from Cuba in various American collections, hence 
one may easily verify the fact, noted by Wheeler in 1910, that speci- 
mens of planatus coming from the United States are the same as the 
typical Cuban form. The difficulty lies in overcoming Emery's er- 
roneous concept of the character of these specimens. Perhaps it would 
be more palatable to those who have accepted Emery's view if they 
realize that the facts stated by Wheeler do not necessarily invalidate 
the status of the subspecies continentis. Since the types of continentis 
came from Guatemala, it would not be surprising if they show a struc- 
tural difference from those of northern Mexico, the southern United 
States and Cuba. But it is no paradox to say that the status of con- 
tinentis can only be defended by giving up the idea that it is as inclu- 
sive as Emery supposed. For those who insist that our representa- 
tives of planatus belong to the subspecies continentis are actually ar- 
guing that continentis is a synonym of the typical planatus. 

The habits of planatus have been repeatedly studied. The insect is 
arboreal and constructs its nests in decayed branches, hollow twigs 
and in the bases of bromeliads. The colonies are small and hard to 
find but the individual ants are conspicuous because of their foraging 
activities. They like to run along vines and are surprisingly difficult 
to catch, since they dodge around to the rear of the vine when dis- 
turbed. Very little is known of the habits of mina subsp. zuni but it 
is probable that it is not so thoroughly arboreal as is planatus. 

Key to the species of Myrmobrachys 

1. Antennal scapes of the major slightly surpassing the posterior corners of 

the head; head and thorax deep, ferrugineous red planatus 

Antennal scapes of the major reaching but not surpassing the posterior 
corners of the head; head, thorax and gaster black mina subsp. zuni 



44. CAMPONOTUS (MYRMOBRACHYS) PLANATUS Roger 

C. planatus Roger, Berl. Ent. Zeitschr., Vol. 7, p. 148 (1863) 9 9 rf 1 ; Forel, 

Biol. Centrali Amer. Hym., Vol. 3, p. 141 (1899); Forel, Ann. Soc. Ent. 

Belg., Vol. 45, p. 371 (1901); Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, 

p. 348 (1910) 9 9 cf . 
C. (M.) planatus M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 608, 

pi. 19, fig. 74 (1947) 9 . 

Type loc: Sarabanda, Cienaga de Zapata, Cuba. Types: none in this country. 
Range: Cuba, southern Florida, the Brownsville area of Texas and northern 

Mexico. 



CEEIGHTON: ANTS OF NORTH AMERICA 6yy 

45. CAMPONOTUS (MYRMOBRACHYS) MINA ZUNI Wheeler 

C. mina subsp. zuni Wheeler, Ann. N. Y. Acad. ScL, Vol. 20, p. 346 (1910) 9 91 . 

Typeloe: Tucson, Arizona. Types: M.C.Z., A.M.N.H. 

Range: rather widely distributed in southern Arizona. A number of the 

records come from low elevations in mountain ranges but the insect also 

occurs in open desert flats. 



Subgenus MYRMAPHAENUS Emery 

Since the publication of the formicine section of the Genera In- 
sectorum in 1925, it has been customary to follow Emery in his alloca- 
tion of the species bruesi and yogi to the subgenus Myrmaphaenus. 
The present treatment does not depart from this practice, but it seems 
well to note certain weaknesses of the subgenus Myrmaphaenus which 
may make further revision necessary when some of the constituent 
species are better known. Up to the year 1920, most of the species at 
present in Myrmaphaenus had been a part of a larger assemblage to 
which Forel gave the subgeneric name Myrmamblys in 1912. As 
originally constituted, Myrmamblys contained species from both the 
Old World and the New World tropics. The common structural fea- 
tures which were supposed to mark this group were a medium stature, 
an elongate head with the sides parallel or nearly so and with the upper 
surface often obliquely truncate. The media caste was frequently 
absent which resulted in a strong dimorphism in most species. But 
it was freely admitted that a number of species originally included 
in Myrmamblys failed to meet all the above criteria. Thus, from the 
outset, the subgenus possessed a degree of heterogeniety that was 
high, even for a subgenus of Camponotus. In 1920 Emery attempted 
to better this situation by removing from Myrmamblys a small num- 
ber of Neotropical species which he placed in the new subgenus Myrma- 
phaenus. At the same time he restricted the subgenus Myrmamblys 
to those species previously known as the novogranadensis and capperi 
groups and erected two other subgenera to receive the Old World 
Myrmamblys (Myrmotemnus) and the New World salvlni group 
(Paracolobopsis). It is to be regretted that Emery failed in this at- 
tempt for in many respects his plan is superior to the present arrange- 
ment. But Emery had neglected the fact that Wheeler had designated 
reticulatus as the subgenotype of Myrmamblys in 1913. This meant 
that the name Myrmamblys would have to be applied to the Old 
World species and that Emery's Myrmotemnus would fall as a syn- 
onym of Myrmamblys. It also meant that a new name would be 
necessary for the species of the novogranadensis and capperi groups 



400 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

and for this subgenus Wheeler proposed the name Neomyrmamblys. 
All this was strictly legal and proper but it seems to have been more 
than Emery could stand. For once he lost his temper to the extent 
that he preferred to jettison his own work rather than accept Wheeler's 
proposal. There was nothing he could do about the .name Myrm- 
amblys, which had to be applied to the subgenus containing the Old 
World species. But he could and did block the use of Wheeler's name 
Neomyrmamblys by the simple, though unfortunate, expedient of 
expanding the subgenus Myrmaphaenus to include all the New World 
species which he had divided into three subgeneric groups five years 
earlier. His own subgenus Paracolobopsis disappeared along with 
Wheeler's Neomyrmamblys and the reconstructed subgenus Myrma- 
phaenus which resulted was scarcely less heterogeneous than was the 
old subgenus JVlyrmamblys from which it had been split. 

I have presented the above discussion because it is necessary to 
appreciate that the diversity of structure in the subgenus Myrma- 
phaenus permits an unusually wide latitude in the case of the species 
which may be included in it. This causes little difficulty as far as the 
species bruesi is concerned, since this insect is closely related to other 
species in the novogranadensis complex and will have to be included 
with them regardless of any subdivisions which may later be made in 
the subgenus Myrmaphaenus. Emery was clearly convinced that 
yogi falls into this category also, but his view is by no means con- 
vincing. As I shall show, there is no way at present of exactly deter- 
mining the subgeneric status of yogi. The species was described by 
Wheeler in 1915 from two specimens, a major and a minor worker. 
As far as I have been able to ascertain, these specimens were the only 
representatives of this species ever taken. At the time when WTieeler 
described yogi, he was of the opinion that it was related to the sub- 
genus Colobopsis, but he did not commit himself on this point in 1915. 
Two years later, however, he definitely assigned yogi to the subgenus 
Colobopsis. It is important to remember in this connection that in 
1917 the old subgenus Myrmamblys had been in existence for five 
years. Moreover Wheeler had, in 1913, proposed reticulatus as its 
subgenotype. We cannot suppose that Wheeler was not aware of the 
general characteristics of the subgenus Myrmamblys and the con- 
clusion is inescapable that when he assigned yogi to Colobopsis, he 
did so because he felt that it fitted better there than in Myrmamblys. 
It is not easy, under such circumstances, to justify Emery's contrary 
opinion. On the other hand, it is equally difficult to disprove it. 
Emery undoubtedly used Wheeler's description of yogi as the basis 
for his allocation of that species to Myrmaphaenus. Those who seek 
to clarify the situation will be forced to follow suit, for the types of 



CREIGHTON: ANTS OF NORTH AMERICA 4Ui 

yogi are either lost or misplaced. I have been unable to find them in 
the collection of the Museum of Comparative Zoology or in that of 
the American Museum of Natural History. For this reason I have 
acceded to Emery's treatment of yogi, for as things stand now any 
additional opinion on the status of yogi may make the existing con- 
fusion worse. 

Little is known about the habits of bruesi and yogi. The types of 
bruesi were taken on the trunk of an acacia tree at Ft. Davis, Texas. 
The insect is fairly common on the small oaks which occur at the 
mouths of several of the canyons in the Huachuca Mountains. They 
are very active and rather timid insects and the nests are difficult to 
find. After much searching I found several clusters of workers under 
the loose bark of partially decayed branches. I do not think that any 
one of these clusters could have been the main part of the nest. They 
seemed to be superficial parts of nests whose main passages followed 
areas of decaying wood deep in the branches and trunk of the trees. 
The two type specimens of yogi were taken from a hollow twig of 
manzanita. 



Key to the species of Myrmaphaenus 

Antennal scapes of the major reaching the posterior corners of the head; 

frontal lobes divergent anteriorly; color testaceous yellow yogi 

Antennal scapes of the major surpassing the posterior corners of the head 
by one third of their length; frontal lobes parallel anteriorly; color piceous 
black with the front of the head brownish brues 



46. CAMPONOTUS (MYRMAPHAENUS) BRUESI Wheeler 

C. bruesi Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 3ft9 (1910) 9 01. 

C. (M.) bruesi M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, p. 608, 

pi. 19, fig. 72 (1947) 2t. 

Type loc: Ft. Davis, Texas. Types: M.C.Z., A.M.N.H. 
Range: western Texas to southern Arizona and south into Mexico. 



47. CAMPONOTUS (MYRMAPHAENUS) YOGI Wheeler 

C. yogi Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 34, p. 420 (1915) 9 21. 
Type loc: Point Loma, San Diego, California. Types: apparently lost or 

misplaced. 
Range: known only from type material. 



402 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOG\ 

Subgenus MANNIELLA Wheeler 

The subgenus Manniella was set up by Wheeler in 1921 to receive 
the Cuban species sphaericus and its subspecies sphaeralis. Emery 
later placed ulcerosus in this subgenus. I have followed Emery's 
treatment in this work, although it must be confessed that the two 
species show a rather striking difference in cephalic structure of the 
major. The peculiar ulcer- like concavities which give ulcerosus its 
name are entirely confined to the cheeks and do not involve the frontal 
lobes. The latter are of normal configuration. In the major of sphaeri- 
cus the depressed areas occur not only on the cheeks but also involve 
the anterior part of the frontal lobes. The two species thus present 
a very different appearance. Since the subgenus Manniella was based 
mainly on the cephalic structure of sphaericus, it follows that ulcerosus 
does not fit too well in the subgenus. But it is certainly better there 
than in Colobopsis, to which Forel attempted to assign it. For the 
head of ulcerosus is not cylindrical in cross section and the angle of 
truncation is very oblique, so that when the head is seen from the side 
its outline is that of a stubby wedge. The unique structural features 
which mark the major of ulcerosus are not found in the minor. These 
are remarkably like the minors of bruesi and differ from them mainly 
by their slightly larger size and more abundant erect body hairs. 
The minors of ulcerosus are also a little less shining than those of 
bruesi. The coloration of the two is virtually identical. 

The habits of ulcerosus also indicate that it cannot properly be 
grouped with Colobopsis. The nests which Wheeler found in the 
Huachuca Mountains were built under large stones. 



48. CAMPONOTUS (MANNIELLA) ULCEROSUS Wheele 

C. ulcerosus Wheeler, Ann. N. Y. Acad. Sci., Vol. 20, p. 351 (1910) 01. 

C. (M.) ulcerosus Emery, in Wytsman, Genera Insectorum, Fasc. 183, pi. 3, 

fig. 12 (1925) 01 ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 

p. 608, pi. 19, fig. 73 (1947) 01. 

Type loc: Parmerlee, Huachuca Mountains, Arizona. Types: A.M.N.H. 
Range: mountains of southern Arizona at elevations of 5000-6000 feet. 



Genus PARATRECHINA Motschoulsky 
(Plate 51, figures 1-4) 

The situation which exists in the taxonomy of Paratrechina is most 
depressing. At present the genus is in a condition which looks very 
much like a hopeless muddle. Nor is there much that can be done to 



CREIGHTON: ANTS OF NORTH AMERICA 4Uo 

improve the matter until someone is willing to undertake the arduous 
and extensive revisionary work that is so obviously needed. Much 
of this difficulty can be traced to the fact that specific distinctions in 
this genus are, at best, very subtle. This should have been enough to 
place a check on the description of subspecies and varieties in this 
group, and most myrmecologists seem to have appreciated this clearly. 
But Forel had no such compunctions and proceeded to load up cer- 
tain species (vividula, fuha, bourbonica, etc.) with such a plethora of 
varieties and subspecies that these species have gone to pieces under 
the strain. It is no novelty to find such complexes in formicid tax- 
onomy, and those in the subgenus Nylanderia are smaller than some 
which occur in other genera, but there is one unusual difference. In 
Nylanderia the structural distinctions which mark many of the sub- 
species are entirely comparable to specific differences elsewhere in the 
group. It is extremely difficult to deal with such a situation in a logi- 
cal fashion, for the extent of specific limits in Nylanderia is a much 
more arbitrary matter than is usually the case with ant genera. There 
can be little doubt that these considerations have played a large part 
in turning the attention of myrmecologists to genitalic differences in 
the males of Nylanderia. Extensive use has been made of the structure 
of the middle genital valve as an index of specificity, but even with 
this as an aid the difficulties have not been invariably overcome. In 
many cases the differences shown by the male genitalia are less pro- 
nounced than could be wished, thus even this supposedly infallible 
criterion is open to different interpretations. It would seem that the 
most promising solution for the difficulties of this forbidding group 
may lie in zoogeographical analysis. At least this method should en- 
able us to establish with reasonable certainty which forms are species 
and which are subspecies. This will, however, be no easy task, for 
the widespread distribution of the group in the warmer parts of the 
world and the vagrant tendencies of many of the species make this 
type of analysis exceptionally difficult. 

The habits of our representatives of Paratrechina are not very 
striking and as long as these insects remain outdoors they seldom at- 
tract much attention. Occasionally, however, they make pests of 
themselves by entering dwellings or greenhouses. The imported 
longicornis is particularly liable to do so. The species often make 
nests in the soil which are surmounted by small, irregular craters of 
excavated earth. At other times they nest under stones or beneath 
moss. They feed upon honey-dew from aphids, nectar and the tissues 
of other insects. 

The following key does not contain the undetermined form of 
bourbonica which has been taken in Florida and South Carolina. The 
reason for this omission is explained on a subsequent page. 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 



Key to the species of Paratrechina 

1. Antennal scapes at least twice as long as the head; body with distinct blue 

or violaceous reflections (Subgenus Paratrechina) longicornis 

Antennal scapes less than twice as long as the head; body without violaceous 
reflections (Subgenus Nylanderia) 2 

2. Antennal scapes without erect hairs parvida 

Antennal scapes with at least a few erect hairs on the anterior surfaces, 
usually many more present 3 

3. Length 4-4.5 mm.; erect hairs abundant on all surfaces of the tibiae; 

appressed pubescence prominent on the head and gaster fulva 

Length 3 mm. or less; erect hairs on the tibiae mainly confined to the 
extensor surfaces; appressed pubescence absent or very obscure on the head 
and gaster 4 

4. Erect hairs on the antennal scapes abundant and occurring on the sides as 

well as the front of the scape, absent only from the rear surface 5 

Erect hairs on the antennal scapes sparse and almost entirely confined to 
a single row on the front of the scape 6 

5. Color clear yellow vividula subsp. guatemalensis 

Color piceous brown vividula 

6. Antennal scapes surpassing the occipital margin by only a little less than 

half their length 7 

Antennal scapes surpassing the occipital margin by not more than one-third 
their length bruesi 

7. Head (except in very small workers) as broad as long or a little broader 
than long; erect hairs on the upper surface of the body rather sparse and 

not very long melanderi 

Head a little longer than broad; erect hairs on the upper surface of the 
body long and abundant melanderi subsp. arenivaga 



Subgenus PARATRECHINA Motschoulsky 

1 . PARATRECHINA LONGICORNIS (Latreille) 
(Introduced) 

Formica longicornis Latreille, Fourmis, p. 113 (1802) 9 . 

Paratrechina longicornis Emery in Wytsman Genera Insectorum, Fasc. 183, 

pi. 4, fig. 8, 8a (1925) 9 cT ; M. R. Smith, Amer. Mid. Naturalist, Vol. 37, 

No. 3, p. 610, pi. 20, fig. 75 (1947) 9 . 
Prenolepis longicornis Roger,. Verz. Formicid., p. 10 (1863); Mayr, Reise 

Novara Formicid., p. 50 (1865) 9 ; Mayr, Tijdschr. v. Ent., Vol. 10, p. 72 

(1867) 9 9; E. Andr6, Ann. Soc.'Ent. Fr. (6), Vol. 1, p. 60 (1891) tf; 

E. Andre, Spec. Hym. Europe, Vol. 2, p. 203 (1882) 9 9 c?; Forel, in 

Grandidier, Hist. Nat. Madagascar, Vol. 20 (2), p. 81, pi. 2, fig. 8 (1891) <?; 

Forel, Jour. Bombay Nat. Hist. Soc., Vol. 8, p. 406 (1894) 9 cf ; Bingham, 



CEEIGHTON: ANTS OF NORTH AMERICA 405 

Fauna Brit. India Hym., Vol. 2, p. 326 (1903) 9 9 0" ; Arnold, Ann. S. 

African Mus., Vol. 14, p. 605 (1922) 9 9 d 1 . 
Prenolepis (Nylanderia) langicornis Emery, Deutseh. Ent. Zeitschr., p. 129, 

fig. 2, 3 (1910) 9 9 cf; Emery, Nova Caledonia Zool., Vol. 1, p. 422, nota 

(1914) 9. 

Formica vagans Jerdon, Madras Jour. Lit. Sci., Vol. 17, p. 124 (1851) 9 . 
Formica gracikscens Nylander, Ann. Sci. Nat. Zool. (4), Vol. 5, p. 73, pi. 3, 

fig. 20 (1856) 9 . 

Tapinoma gracikscens F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 56 (1858). 
Paratrechina currens Motschoulsky, Bull. Soc. Nat. Moscow, Vol. 36, p. 14 

(1863) 9. 

Type loc: Senegal, Africa. Types: none in this country. 
Range: (in the United States) Florida to South Carolina and west to Texas 

and sporadically in residences, warehouses and greenhouses over much of 

the eastern United States. 

This well known tropicopolitan species appears to be well estab- 
lished in the Gulf Coast area and it seems likely that in this area it 
can survive winter climate in the field. Climate, however, is not much 
of a hazard for this enterprising insect, for it adapts itself to life in- 
doors with great readiness in northern stations. The ant is surpris- 
ingly abundant in New York City, where it infests warehouses and 
apartments. 



Subgenus NYLANDERIA Emery 

2. PARATRECHINA (NYLANDERIA) BOTJRBONICA Forel var.? 
(Introduced) 

The treatment which has been accorded this insect will show the 
hopeless confusion which exists in the case of some of the larger com- 
plexes in Nylanderia. Both Wheeler and M. R. Smith have reported 
a form of bourbonica from Florida but neither of them have attempted 
to state which variety is represented. Since Wheeler seemed certain 
that the insect had been introduced from the Orient, it may be as- 
sumed that it is at least related to the subspecies amia, which is the 
form most commonly encountered in southeastern Asia. Unfortun- 
ately I failed to examine this insect in the Wheeler Collection for I 
was under the impression that the form involved was the typical 
bourbonica. If the Florida material is, as I suppose, related to amia, it 
will run down in the key to vividula, from which it will differ in its 
lower and more evenly convex promesonotum which rises gradually 
from the mesoepinotal suture and has no distinct declivious face at 



406 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

the rear. It should be obvious why it is impossible to present biblio- 
graphic references for this insect, although I am ready to admit that 
if I had been a little more alert, it might have been possible to do so. 

3. PARATRECHINA (NYLANDERIA) BRUESI (Wheeler) 

Prenolepis bruesi Wheeler, Psyche, Vol. 10, p. 106, fig. 9 (1903) 9 9 cf. 
Type loc: Fresno Canyon, Presidio County, Texas. Types: A.M.N.H., 

M.C.Z. 
Range : southwestern Texas along the Gulf Coast to southern Alabama. 

Wheeler seems to have slightly overestimated the scape length of 
bruesi. In the original description of bruesi the length given for the 
scape is the same as that for melanderi. It is my opinion that the scape 
of bruesi is notably shorter than that of melanderi and this seems to 
be the best feature for the separation of these two species. The in- 
sect which Pergande described as P. anthracina var. nodifera in 1895 
was associated by Emery with bruesi. This association seems scarcely 
justified in view of the differences which may be observed in Per- 
gande's description. There is also the difficulty that Pergande's ma- 
terial came from central Mexico and the tip of Lower California. 
Further study will be needed to determine the nature of Pergande's 
material but it would seem unnecessary to carry the reference to his 
description in the bibliography of bruesi any longer. 



4. PARATRECHINA (NYLANDERIA) FULVA (Mayr) 
(Introduced) 

Prenolepis fulva Mayr, Verh. Zool-bot. Ges. Wien, Vol. 12, p. 698 (1862) 9 9 ; 

Mayr, Reise Novara Formicid., p. 51, pi. 2, fig. 14 (1865) 9 9 ; Mayr, 

Zool-bot. Ges. Wien, Vol. 20, p. 947 (1870) 9 ; Forel, in Grandidier Hist. 

Nat. Madagascar, Vol. 2 (2), p. 93, pi. 3, fig. 3 (1891) d"; Emery, Nova 
v Caledonia Zool., Vol. 1, p. 422 nota (1914) 9 . 
P. fulva subsp. pubens Emery, Zool. Jahrb. Syst,, Vol. 7, p. 636, pi. 22, fig. 24 

(1893) 9 cT. 

Type loc: Brazil. Types: none in this country. 
Range: (in the United States) extreme southern Texas and sporadically in 

greenhouses as far north as New Jersey. 

There has been much confusion regarding this insect. Prior to 1893 
Pergande sent specimens from Washington, which he had secured in 
a hot house belonging to the Department of Agriculture, to Emery 
and Forel. The specimens were used by Forel as a part of the type 



CREIGHTON: ANTS or NOKTH AMERICA 4U/ 

series for the subspecies pubens, which he described from the Wash- 
ington material and other specimens coming from St. Vincent, B.W.I. 
Emery stated flatly that the workers of Pergande's material were iden- 
tical with those of the typical fulva from Brazil. However, Emery 
managed to ennumerate some slight differences in the case of the 
male. The head of this insect was a little longer than that of the type 
and its outer genital valve was a trifle more hairy. But Emery could 
see no difference in the structure of the median genital valve, which 
usually is the part most relied upon for specific differences. It seems 
to the writer that Emery's efforts to support Forel only proved all the 
more conclusively that Forel was incorrect in his treatment of the 
specimens which he had from Pergande. This does not mean that 
Forel's pubens must be considered a synonym of fulva for the specimens 
from St. Vincent may be subspecifically distinct. But it does mean 
that specimens from the United States which we have been calling 
pubens are actually the typical fulva. There is no room for doubt on 
this score for the agreement between our specimens and those from 
Brazil is startling. It is of interest to note that while all of the northern 
records of fulva have come from greenhouses, the insect has acclimated 
itself to outside conditions in extreme southern Texas. I have before 
me a series of workers taken in the field at Brownsville by Dr. P. J. 
Darlington. 



5. PAHATRECHINA (NYLANDERIA) MELANDERI (Wheeler) 

Prenolepis melanderi Wheeler, Psyche, Vol. 10, p. 104, fig. 8 (1903) 9 9 cf. 
P. (N.) vividula subsp. melanderi Emery, Ann. Soc. Ent. Belg., Vol. 50, p. 132, 

fig. 5 (1906) cf. 
Typeloc: New Braunf els, Texas (by present restriction). Types: A.M.N.H., 

M.C.Z:, Coll. W. S. Creighton. 
~ :e: Tennessee to western Texas and south into Mexico. 



I cannot agree with Emery that melanderi ought to be treated as a 
subspecies of vividula. Emery's association was based in large part on 
a consideration of genitalic structure in the male and his reasons for 
arriving at this decision are far from compelling. Emery could not 
claim that the genitalia of melanderi are identical with those of vivi- 
dula, for they certainly are not. But Emery considered the similarity 
sufficiently close to warrant associating the two forms. This, of course, 
is entirely a matter of how one wishes to interpret existing differences 
and these same differences could be cited in support of the separate 
specificity of melanderi. But it would seem unnecessary in this case 
to put so much stress on male structure, since there are significant 



408 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

differences which separate the worker of melanderi from that of viiii- 
dula. In the first place, there is a notable difference in head shape in 
the two species. Because the shape of the head varies slightly with 
the size of the worker, it is difficult to generalize in this matter. But 
it may be said that the head of vividula is usually narrower behind the 
eyes than in front of them, with the occipital angles notably rounded. 
In no case is the head of vividula broader at the rear than in front al- 
though in some specimens the width is about the same at the front 
and the rear of the head. In melanderi this situation is reversed. The 
head is usually broader behind the eyes than in front of them and 
never narrower at the occiput than at the insertion of the mandibles. 
But one may as well admit that it is possible to select from each species 
individuals in which the head shape is very similar. These, however, 
seem to be the exception and not the rule. A difference which is much 
more constant, although of less magnitude, is the pilosity of the scapes. 
This difference is given in the key and need not be repeated here, but 
it may be said that it will hold for every form of vividula which the 
writer has been able to examine and would, therefore, seem to be a 
very useful distinction. 

I further believe that arenivaga will have to be considered as a sub- 
species of melanderi. This is an interesting point, for it may be re- 
called that Emery was perfectly willing to accord separate specific 
status to arenivaga although denying it to melanderi. 

6. PAEATRECHINA (NTLANDEEIA) MELANDEBI AEENIVAGA (Wheeler) 

Prenokpis arenivaga Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 391, 

fig. 3 (1905) 9 d". 
Prenolepis arenivaga var. faisonensis Forel, Rev. Suisse Zool., Vol. 30, p. 98 

(1923) 9. 

Type loe: Lakehurst, New Jersey. Types: A.M.N.H., M.C.Z. 
Range: New Jersey to the Gulf Coast. 

The worker of arenivaga is so similar to that of melanderi that its 
status as a separate species could scarcely have been defended had it 
not been for the differences which Wheeler described in the genitalia 
of the male. Wheeler's figures of the median genital valve of arenivaga 
show a bilobed structure in which the two lobes are of approximately 
the same length. In melanderi the inner lobe is much shorter than the 
outer one and curved against it. The writer has examined the geni- 
talia of a number of males of arenivaga taken in the type locality and 
has found that in every case they are much more like Wheeler's figure 
of melanderi than his figure of arenivaga. In point of fact they do not 
seem to resemble the figure of arenivaga at all. The inner lobe is less 



CREIGHTON: ANTS OF NORTH AMERICA 4UW 

than half as long as the outer and has its tip curved against a row of 
tiny tubercles which extend along the side of the outer lobe (as in 
melanderi). The conspicuous terminal cluster of tubercles which 
Wheeler shows in his figure of arenivaga is entirely absent. I confess 
that I cannot easily account for these discrepancies, but I feel certain 
that the male genitafia of arenivaga are much more like those of 
melanderi than Wheeler supposed. Finally I believe that I have fairly 
conclusive evidence, from specimens taken in southern Alabama, to 
show that melanderi and arenivaga intergrade in that area. For the 
above reasons I have treated arenivaga as a subspecies of melanderi. 
Forel's variety faisonensis is, in my opinion, a straight synonym of 
arenivaga. 

7. PARATRECHINA (NYLANDERIA) PARVULA (Mayr) 

Preriolepis parvula Mayr, Verh. Zool-bot. Ges. Wien, Vol. 20, p. 948 
(1870) 9 9 cf; Emery, Zool. Jahrb. Syst., Vol. 7, p. 636, pi. 22, fig. 23 
(1893) d"; Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 21, p. 390, fig. 2 
(1905) d". 

P. (Nylanderia) parvula M. R. Smith, Amer. Mid. Naturalist, Vol. 37, No. 3, 
p. 610, pi. 20, fig. 76 (1947) 9 . 

Prenolepis vividula subsp. parvula Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 20, 
p. 348 (1884). 

Prenolepis parvula var. grandula Forel, Rev. Suisse Zool., Vol. 30, p. 98 (1923) 9 . 

Type loc: New York. Types: none in this country. 

Range: southern New York west to Iowa, south to Florida and southwest to 
Texas. 

Forel's variety grandula is nothing more than one of the slight 
fluctuations in size and color which appear over the entire range of 
parvula. The color of this species is particularly variable. Specimens 
from the southern part of the range are sometimes pale yellow with 
only the gaster slightly infuscated. There is, however, nothing that 
would indicate that these fluctuations have any distributional signifi- 
cance. On the other hand the absence of erect hairs on the scapes of 
this species seems to be a highly constant and very reliable separatory 
feature. The writer has never seen the slightest tendency toward in- 
termediate conditions in this character. 



8. PARATRECHINA (NYLANDERIA) VIVIDULA (Nylander) 
(Introduced) 

Formica vividula Nylander, Acta. Soc. Sci. Fennic., Vol. 2, p. 900, pi. 18, fig. 

2, 10-14 (1846) 9 9 <?. 
Prenolepis vividula Mayr, Europ. Formicid., p. 52 nota (1861). 



410 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY 

Prenolepis (Nylanderia) vividula Emery, Ann. Soc. Ent. Belg., Vol. 50, p. 130, 
fig. 1-4 (1906); Wheeler, Bull. Amer. Mus. Nat. Hist., Vol. 24, p. 154 
(1908); Emery, Deutsch. Ent. Zeitschr., p. 131, fig. 6, 7 (1910) 9 9 cf; 
Emery, Nova Caledonia Zool., Vol. 1, p. 422 nota (1914) 9 . 

Formica vividula Nylander, Ann. Sci. Nat. Zool. (4), Vol. 5, p. 66, pi. 3, fig. 
5, 21 (1856) 9 9 d". 

Tapinoma vividula F. Smith, Cat. Hym. Brit. Mus., Vol. 6, p. 56 (1858). 

Typeloc: Antilles? Types: none in this country. 

Range: (in the United States) Florida and Mississippi and sporadically in 
greenhouses in many parts of the country. 



9. PAKATHECHINA (NYLANDERIA) VIVIDULA GUATEMALENSIS (Forel) 

(Introduced?) 

Prenolepis guatemalensis Forel, Bull. Soc. Vaud. Sci. Nat., Vol. 20, p. 348 
(1884) 9 ; Forel, Trans. Ent. Soc. Lond., p. 340 (1893); Emery, Nova 
Caledonia Zool., Vol. 1, p. 422 nota (1914) 9 ; Wheeler, Bull. Amer. Mus. 
Nat. Hist., Vol. 21, p. 392, fig. 4 (1905) d". 

Prenolepis (Nylanderia) vivid^da var. guatemalensis Forel, Mem. Soc. Ent. 
Belg., Vol. 20, p. 66 (1912). 

Typeloc: Guatemala. Types: A.M.N.H., M.C.Z. 

Range : (in the United States) southern Arizona. 

As far as the writer has been able to determine the only record for 
guatemalensis in the United States is the one published by Emery in 
1893. This record was based on a single worker taken in Phoenix, 
Arizona. The absence of any further records make it seem very likely 
that the insect failed to establish itself in that area. 



Genus PRENOLEPIS Mayr 
(Plate 52, figures 1-4) 

In 1930 Wheeler published an exhaustive account of the biology of 
Prenolepis imparis. The first part of this paper dealt with the habits, 
distribution and paleontological relationships of the insect. The second 
part was devoted to its taxonomy. In addition to the typical form 
Wheeler recognized nine varieties. Certain paleontological consider- 
ations with which Wheeler dealt seem to have had a considerable effect 
on his taxonomic treatment of imparis. It may be recalled that 
Wheeler believed that our present day representatives of imparis are 
scarcely more than varieties of the fossil Prenolepis henschei of the 
Baltic amber. Since Wheeler was defending the thesis that there has 



CREIGHTON: ANTS OF NORTH AMERICA 411 

been little change in this ant since the Oligocene, he relegated all the 
forms to the lowest taxonomic rank, the variety, although he con- 
sidered that some of them represented 'incipient geographical races'. 
The importance of Wheeler's paleontological deductions need not be 
questioned, but it seems a dubious business to make them the basis 
for present day taxonomy. Despite the fact that imparis is, as Wheeler 
put it, '